Tuesday, September 6, 2016

Irony of Automation in Aviation

These statements are so true!

Computers do those things well that pilots already know how to do well, much better than pilots. But computers do not know how to do those things that a pilot would like to do well.

   In essence, the irony is that pilots are to oversee an automated system, which they do poorly, and take over when there are abnormal conditions, which they may not be very good at either.

-----------------ATPL Book 8 CAE Oxford Aviation Academy

Monday, May 9, 2016


HELIOS AIRWAYS FLIGHT 522: 14 AUG 2005: BOEING 737 – 300


On 14 Aug 2005, Helios Airways international Flight 522 departed from Larnaca, Cyprus, at 06:07h for an intermediate stop at Athens, Greece on way to Prague, Czech Republic. The planned flying time was 1 hour and 23 minutes. While climbing through an altitude of 12040 ft, for FL 340, the cabin altitude warning horn sounded at 06:12h. The German captain and the Cypriot co-pilot tried to solve the problem but encountered some problems communicating with each other.

Helios' Boeing 737-300 5B-DBY underwent maintenance on the night prior to the accident. The pressurization system was checked, but after completion of the tests the Pressurization Mode Selector (PMS) was reportedly left in the "Manual" position instead of the "Auto" mode. In manual mode the crew had to manually open or close the outflow valves in order to control the cabin pressure. The outflow valves were one-third in the open position which meant that the cabin would not pressurize after takeoff. The PMS mode was apparently not noted during the pre-departure checks by the crew.

At 06:14h while climbing through an altitude of 15966 ft, the Captain contacted the Company Operations Centre (COC) and informed, “Take off configuration warning ON” and “Cooling equipment Normal and Alternate Offline”. Because of a lack of cooling air another alarm activated, indicating a temperature warning for the avionics bay. 

There were a few communications between the Captain and the COC during the period of 06:14h and 06:20h. On a query from the Captain, “where are my equipment cooling circuit breakers?” The engineer replied, “Behind the Captain’s seat”. These needed to be pulled out to turn off the alarm. The captain got up from his seat to look for the circuit breakers. At 06:20h, the Captain made his last communication, at which time the aircraft was climbing through 28900 ft.

During the communications between the Captain and the COC, at an altitude of approx. 18000 ft, the cabin altitude exceeded 14000 ft, leading to the deployment of oxygen masks in the passenger cabin, as per design.

The crew was not wearing their oxygen masks as their mindset and actions were determined by the preconception that the problems were not related to the lack of cabin pressure. As the airplane was still climbing, the lack of oxygen seriously impaired the flight crew. The captain probably became unconscious when he was trying to find the circuit breaker. The first officer was still in his seat when he also became unconscious. There were no further two way communications with the aircraft after 06:20h.

The aircraft continued to climb and leveled out at FL 340, as programmed. The aircraft continued on track maintaining FL 340 and eventually fed in to a standard instrument approach procedure for runway 03L at Athens International airport, while continuing to maintain FL 340. The approach was followed by a missed approach, and setting up of a holding pattern over KEA VOR, while continuing to maintain altitude.

All efforts by Greek air traffic controllers to contact the pilots were futile. Around 07:00h, two Greek F-16 fighter planes were scrambled to intercept the aircraft. The F-16s intercepted the aircraft on its sixth holding pattern, at about 07:23h. The F-16 pilots reported that they were not able to observe the captain, while the first officer seemed to be unconscious and slumped over the controls. Oxygen masks were reported to be dangling in a dark passenger cabin.

At 08:49h, the F-16's reported a person not wearing an oxygen mask entering the cockpit and occupying the captain's seat. The F-16 pilot tried to attract his attention without success. At 08:50h, the left engine flamed out due to fuel depletion and the aircraft started descending. At 08:54h, two Mayday messages were recorded on the CVR, in a very weak voice. At 09:00h, the right engine also flamed out at an altitude of 7084 ft. The aircraft continued descending rapidly and impacted hilly terrain about 33 kms northwest of Athens, close to Grammatiko village.

All 121 persons on board the aircraft, including 6 crew members and 115 passengers, were fatally injured during the accident.

1. Non-recognition that the cabin pressurization mode selector was in the MAN (manual) position during the performance of the:
a) Pre-flight procedure;
b) Before Start checklist; and
c) After Takeoff checklist.

Image Courtesy: Google Images. Pressurisation Mode Selector in Manual Mode

2. Non-identification of the warnings and the reasons for the activation of the warnings (cabin altitude warning horn, passenger oxygen masks deployment indication, Master Caution), and continuation of the climb. (The initial actions by the flight crew to disconnect the autopilot, to retard and then again advance the throttles, indicated that it interpreted the warning horn as a Takeoff Configuration Warning). (At an aircraft altitude of 17 000 to 18 000 ft, the Master Caution was activated and was not cancelled for 53 seconds. The reason for its activation may have been either the inadequate cooling of the Equipment or the deployment of the oxygen masks in the cabin. Independently of the Master Caution indication, there are separate indications for both malfunctions on the overhead panel. The flight crew possibly identified the reason for the Master Caution to be only the inadequate cooling of the Equipment that was indicated on the overhead panel, and did not identify the second reason for its activation, i.e., passenger oxygen masks deployment, that was later also indicated on the Overhead panel. The crew became preoccupied with the Equipment Cooling fan situation and did not detect the problem with the pressurization system. The workload in the cockpit during the climb was already high and was exacerbated by the loud warning horn that the flight crew did not cancel).

3. Incapacitation of the flight crew due to hypoxia, resulting in continuation of the flight via the flight management computer and the autopilot, depletion of the fuel and engine flameout, and impact of the aircraft with the ground. (The incorrect interpretation of the reason for the warning horn indicated that the flight crew was not aware of the inadequate pressurization of the aircraft).


1. The Operator’s deficiencies in organization, quality management and safety culture, documented diachronically as findings in numerous audits.

2. The Regulatory Authority’s diachronic inadequate execution of its oversight responsibilities to ensure the safety of operations of the airlines under its supervision and its inadequate responses to findings of deficiencies documented in numerous audits.

3. Inadequate application of Crew Resource Management (CRM) principles by the flight crew.

4. Ineffectiveness and inadequacy of measures taken by the manufacturer in response to previous pressurization incidents in the particular type of aircraft, both with regard to modifications to aircraft systems as well as to guidance to the crews.


1. Omission of returning the pressurization mode selector to AUTO after un-scheduled maintenance on the aircraft.

2. Lack of specific procedures (on an international basis) for cabin crew procedures to address the situation of loss of pressurization, passenger oxygen masks deployment, and continuation of the aircraft ascent (climb).

3. Ineffectiveness of international aviation authorities to enforce implementation of corrective action plans after relevant audits.

Friday, May 6, 2016




Flight 092 left London for Belfast at 19:52h with a crew of 8, and 118 passengers on board. While climbing through FL283 moderate to severe vibration that was accompanied by ingress of smoke and fumes in to the flight deck were felt, as also fluctuations in the engine parameters of the No. 1 engine. Investigations revealed that these were the result of one of the outer panel of one of the no. 1 engine fan blades getting detached in flight, causing a series of compressor stalls that lead to airframe shuddering.

Believing the No. 2 engine had suffered damage, the crew throttled it back. The shuddering stopped, leading the flight crew to believe that their actions were correct, and they thus shut down the No 2 engine. The No. 1 engine operated normally after the initial severe vibrations, and during the descent in to East Midlands, the diversionary airfield.

The flight was cleared for an approach on to runway 27. The instrument approach on No. 1 engine continued normally, although with a high level of vibrations from the live engine. At 900 feet, 2.4nm from the runway, no. 1 engine suddenly suffered a reduction in power followed by a fire warning on this engine. Attempts to restart No. 2 engine were not successful. As the speed fell below 125 knots, the stick shaker activated and the aircraft struck trees at a speed of 115 knots. The aircraft continued and impacted the western carriageway of the M1 motorway 10 m lower and came to rest against the wooded embankment, 900 m short of the runway.

39 passengers died in the accident, and 8 more died later due to the injuries sustained. Of the remaining 79 occupants, 74 suffered serious injuries.

(Image Courtesy: Google Images: Aerial view of Crash site)


The operating crew shut down the No 2 engine after a fan blade had fractured in the No 1 engine. This engine subsequently suffered a major thrust loss due to secondary fan damage after power had been increased during the final approach to land.

The following factors contributed to the incorrect response of the flight crew

1. The combination of heavy engine vibration, noise, shuddering and an associated smell of fire were outside their training and experience.

2. They reacted to the initial engine problem prematurely and in a way that was contrary to their training. (Either pilot does not remember having noticed the engine parameters like N1, EGT, N2 or Oil Pressures of the engines before throttling back No. 2 engine).

3. They did not assimilate the indications on the engine instrument display before they throttled back the No. 2 engine. (The crew’s familiarity of the newly introduced EIS on the B 737-400 variant could have been a factor. The Captain had 23 hours and the first officer had 53 hours on the B 737-400. Both were given a 1day training session on the EIS, as there was no flight simulator available with the EIS. The variants before the B737-400 had the normal electro-mechanical engine instruments).

4. As the No 2 engine was throttled back, the noise and shuddering associated with the surging of the No 1 engine ceased, persuading them that they had correctly identified the defective engine. (The Auto Throttle system was disengaged while bringing No. 2 engine throttle back to idling. This led to manual control of the engines, and No. 1 engine fuel flow settled as per the prevailing engine conditions, rather than as demanded by the auto throttle to maintain flight parameters).

5. They were not informed of the flames which had emanated from the No.1 engine and which had been observed by many on board, including 3 cabin attendants in the aft cabin. (Inadequate communications between flight and cabin crew – a CRM issue that is greatly emphasised now).

Thursday, November 26, 2015

Weak link in the Indigo Airline System

I recently traveled by Indigo from Chandigarh to Bangalore. The flight was perfect with everything that is expected of an airline, starting from check-in; customer service; boarding; in-flight; cabin crew; the flight and of course the hallmark of Indigo - punctuality.
Image: Courtesy - Google Images

However, there was one flaw that seems to stick out, and would stay with me unless something is done about it by the airline. Imagine booking this flight on the Makemytrip website, after having spent an inordinate time trying to book it on the Indigo website. The Indigo website is slow, and has many glitches that forced me to re-enter data and keep refreshing pages.

Probably it has not been upgraded to keep up with the increased traffic loads on the website, caused due to increase in the fleet strength to 97 aircraft now. Or, could it be by design so that the company does not waste resources on a non core function that can be done more efficiently by a third party that has a core business of online reservations. I am not too sure on the philosophy of Indigo on this aspect.

In my opinion a low cost airline survives by cutting costs, and airline owned online booking platforms are one way of keeping costs down, unless Indigo management has now found out a better way to do it.

I am curious to know. Any one who knows this, please share with me on this blog.

Tuesday, November 26, 2013

Stall Recovery Template issued by FAA in June 2012.

Relevant extracts of FAA Advisory Circular 120 - 109 dated 08 Jun 2012, based on the Colgan Air, Air France and other stall related accidents at high and low altitudes.


1. Autopilot and autothrottle………………………………..Disconnect

Rationale: While maintaining the attitude of the airplane, disconnect the autopilot and autothrottle. Ensure the pitch attitude does not increase when disconnecting the autopilot. This may be very important in out-of-trim situations. Manual control is essential to recovery in all situations. Leaving the autopilot or autothrottle connected may result in inadvertent changes or adjustments that may not be easily recognized or appropriate, especially during high workload situations.

2. a) Nose down pitch control…........................................Apply until stall warning is eliminated
 b) Nose down pitch trim…….………………………..….As Needed 

Rationale: a) Reducing the angle of attack is crucial for recovery. This will also address autopilot-induced excessive nose up trim.
b) If the control column does not provide sufficient response, pitch trim may be necessary. However, excessive use of pitch trim may aggravate the condition, or may result in loss of control or high structural loads.

3. Bank…………………………………………………..…….Wings Level 

Rationale: This orients the lift vector for recovery.

4. Thrust …………………………………………….………….As Needed 

Rationale: During a stall recovery, maximum thrust is not always needed. A stall can occur at high thrust or at idle thrust. Therefore, the thrust is to be adjusted accordingly during the recovery. For airplanes with engines installed below the wing, applying maximum thrust may create a strong nose-up pitching moment if airspeed is low. For airplanes with engines mounted above the wings, thrust application creates a helpful pitch-down tendency. For propeller-driven airplanes, thrust application increases the airflow around the wing, assisting in stall recovery.

5. Speed brakes/Spoilers……….…….…………………………..Retract 

Rationale: This will improve lift and stall margin.

6. Return to the desired flightpath.

Rationale: Apply gentle action for recovery to avoid secondary stalls then return to desired flightpath.

Saturday, July 13, 2013


The recent unfortunate accident involving Flight 214, a Boeing-777 aircraft, of Asiana Airlines at San Francisco is a case of a fully serviceable aircraft flying in to the ground in VMC conditions; due to an approach that became increasingly unstabilized with height. Could this accident be averted, had the crew taken a timely decision to go-around? Conditions being VMC, as per the recommendations enumerated below, the approach should have stabilized latest by 500 ft and should have remained so below 500’, to continue with an approach to land. As per reports, the airplane was configured for landing with 30 degrees of flaps and gear down with a target threshold speed of 137 knots. The aircraft descended through an altitude of 1400 ft at 170 kts and slowed down to 149 kts at 1000 feet. The throttles were reportedly at idle and the auto throttle was armed. At 500 feet altitude, 34 seconds prior to impact, the speed dropped to 134 kts, which was just below the target threshold speed. Any speed below the target speed, the approach should have been considered unstabilized, especially below 500 ft in VMC. The situation was allowed to worsen further when the airspeed dropped significantly, reaching 118 knots at 200 feet altitude. Eight seconds prior to impact, the throttles were moved forward. Airspeed reduced further to 112 knots at an altitude of 125 feet. Seven seconds prior to impact, one of the crew members made a call to increase speed. The stick shaker sounded 4 seconds prior to impact. One second later the speed was 103 knots, the lowest recorded by the FDR. One of the crew members made a call for go-around at 1.5 seconds before impact. This was too late to prevent an accident off an approach that was unstabilized. Accidents during the approach and landing (ALA) phase account for a major percentage of all accidents.

Analysis of data collected by a go-around study being conducted by the Flight Safety Foundation’s (FSF) international and European aviation committees has shown that potentially 54 percent of all aircraft accidents in year 2011 could have been prevented by a timely go-around decision by the flight deck crew. Clarifying on the figure of 54%, the FSF director of global programs is quoted to have said that, “this is based on 65 percent of that year’s accidents being in the approach and landing (ALA) phase, and using our analysis that 83 percent of ALAs could be prevented by a go-around decision”. The study has also elaborated that “the majority of accidents over the last 10 years have occurred during the approach, landing and go-around flight phases. The study has also highlighted the fact that the lack of a go-around decision is the leading risk factor in approach and landing accidents and is the primary cause of runway excursions during landing. Yet, less than 5% of unstabilized approaches lead to a go-around.”

Unstabilized approaches have been attributed to various factors, which include company policies, human factors, weather, crew resource management, ATC and automation. The Asiana case can also be attributed to a number of these factors. The crew felt that the auto throttle should have maintained the speed at 137 kts; the PF and PM were not effectively flying and monitoring the flight path and parameters, which permitted the IAS to drop well below the target speed, and the throttles to remain at idle; company culture may have also come into play in this scenario; fatigue after a long flight due to improper work load assignment – there were four pilots on this flight; three of them in the cockpit during the approach. All of these factors that led to the unstabilized approach would have been taken care of, if the crew had made the decision to go around in time. When things are not as planned in aviation, it is always better to have height and speed in hand. In this particular case there were many issues that pointed towards an unstabilized approach. To understand this it is best to study the elements that constitute a stabilized approach.

Stabilized Approach

Stabilized approach concept is all about maintaining a stable speed, descent rate, and vertical/ lateral flight path in the landing configuration. It is felt that a stabilized approach would generally lead to a safe landing, as the crew’s awareness of the horizontal/ vertical flight path; the IAS and the energy-condition of the aircraft would lead to improved overall situational awareness during the approach. Also, flying a stabilized approach permits the crew to devote adequate time and limited human ‘attention resources’ to flying, monitoring, communications, weather conditions, systems check, and most importantly to decision making. As has been brought out earlier, 95% of unstabilized approaches do not lead to a go-around, and this has contributed to 54% of the total accidents in 2011, and the lack of go-around decision is a major risk factor in ALA. It is now an accepted fact that the decision to execute a go-around is no indication of poor performance.

Recommended Elements of a Stabilized Approach

The following recommendations are developed by the Flight Safety Foundation. All approaches should be stabilized by 1,000 feet above airfield elevation (AFE) in instrument meteorological conditions (IMC) and by 500 feet AFE in visual meteorological conditions (VMC). An approach is considered stabilized when all of the following criteria are met:

·                     The airplane is on the correct flight path
·                      Only small changes in heading and pitch are required to maintain the correct flight path
·                     The airplane speed is not more than VREF + 20 knots indicated airspeed and not less than Vref
·                     The airplane is in the correct landing configuration
·                     Sink rate is no greater than 1,000 fpm; if an approach requires a sink rate greater than 1,000 fpm, a special briefing should be conducted
·                     Thrust setting is appropriate for the airplane configuration, and not below the minimum power on approach as defined by the aircraft operating manual.
·                     All briefings and checklists have been conducted.
·                     Specific types of approaches are stabilized if they also fulfill the following:

    • ILS approaches should be flown within one dot of the glide slope and localizer
    • During a circling approach, wings should be level on finals when the airplane reaches 300 feet AFE.
    • Unique approach procedures or abnormal conditions requiring a deviation from the above elements of a stabilized approach require a special briefing.

For safety reasons, an approach that becomes un-stabilized below 1,000 feet AFE in IMC, or below 500 feet AFE in VMC should be discontinued and a go-around executedAlso, stabilized conditions should be maintained throughout the rest of the approach for it to be considered a stabilized approach. If the above criteria cannot be established and maintained at and below 500 feet AFE, initiate a go-around.


Considering the statistics and the facts enumerated above, it is felt that all efforts should be made to fly stabilized approaches, and if due to some reason an approach becomes unstabilized then the decision to go-around should be taken well in time. A well considered, and executed, go-around will go a long way in ensuring safe operations, and enhance safety in aviation.

Monday, July 8, 2013


A Boeing 777-200 of Asiana Airlines with 307 people on board crashes while landing on runway 28L at San Francisco, killing 2 people and injuring 180. The accident took place at about 11:28 am local time on 06 Jul 2013. As per initial reports coming through, the ILS Glide slope for the runway was non-operational for runway 28L at SFO. It appears that the aircraft came in low. Watching the debris trail on the runway, it appears that some portion of the aircraft touched well short of the beginning of the runway, let alone the threshold. Why? 

The aircraft has called finals at 7 miles and every thing appears normal. Has any failure taken place after that; the aircraft has encountered wind shear; or is it just a case of an undershooting approach with the tail portion of the aircraft hitting the snow wall - a vertical wall at the edge of the land/ water junction.

Awaiting further news on the cause of the accident - prima facie appears to be human error, with the aircraft making an undershooting approach in the absence of ILS glide slope information. No news about VASI or other visual approach aids. Weather at the time was VFR.

Wednesday, June 26, 2013


Introduction      What are Standard Operating Procedures (SOPs)? A letter by the US Federal Aviation Administration (FAA) aptly answered this question where in it was stated that, “SOPs are written, tested procedures that are applied uniformly and consistently within an organization and involve all aspects of flight, both normal and non-normal”. It further stated that “SOPs are widely recognized as a basic element of safe aviation operations”. Safety is one of the pre-requisites for mission accomplishment in aviation, and thus the importance of SOPs can never be under estimated.

Design of SOPs

The aircraft manufacturer provides the initial SOPs for the aircraft based on lessons learned from previous operating experience; analyses performed during design; experience gained during development and certification flight testing; and also experience from the route-proving program. These manufacturer-provided SOPs are adopted without change by an aviation organisation, or these are used as the basis for the development of customized SOPs that promote standardisation across the different aircraft fleets in service at the organisation. Company SOPs so developed reflect the organisation’s operating and training philosophies. Thus, SOPs represent the collective wisdom of the aviation community on how operations could be conducted safely.

To ensure safety, training and operations need to be consistent, implying that training and operations should both be conducted as per the SOPs. This can only happen if everyone in the organisation is convinced of the need to follow SOPs. Bringing about this awareness places a great responsibility on the flying supervisory staff.  Instructors and check airman of the operator are required to ensure that crews are made aware of the reasons for SOPs; are trained as per the SOPs, and are also required to enforce the same during routine line operations.

SOPs published by the operator normally include expected procedures that would be utilised during the flight profiles that are used by the operator, including pre & post flight procedures. SOPs lay down the most effective and efficient procedure to execute any task safely. New procedures need to be added to the SOPs, and redundant ones modified/ deleted based on requirements, and also based on experiences gained by the aviation community. To undertake this task, review of SOPs should be an ongoing task, ideally accomplished with suitable feedback from the end user, the flight crew.

All of this is done with an aim of ensuring safe aviation operations. It is now abundantly clear that safety is not dependant only on the training of the crew, but also on good crew coordination as well as optimum crew performance (or good CRM). This can best be ensured if the crew has a shared mental model of each task that is being undertaken. SOPs provide that vital link that can effectively ensure this shared mental model between crew members, with the least communications, because when every crew member is following SOPs, he/ she is aware of what needs to be done; when it needs to be done; and by whom.

To ensure that every crew member follows the SOPs, these procedures should be clear, comprehensive, and readily available to the flight crew members. In addition the crew members should be aware and convinced of the need to follow the SOPs. All this sounds logical but a study of aircraft incidents and accidents indicates that some of these have been caused due to the crew not following the SOPs.

Operational and Human Factors Involved in Deviations from SOPs

To ensure effective compliance with SOPs, it is important to understand why pilots intentionally or inadvertently deviate from the SOPs. In most cases of deviation from SOPs, the procedure that was followed in place of the published procedure seemed appropriate to the crew, for the prevailing situation, considering the information available in the cockpit at the time. However, it was later found that it was either inappropriate, or at best suboptimal. Experts cite the following factors and conditions as making it more likely that a deviation from SOPs will occur. Awareness of these factors can influence adherence to SOPs and may also be useful in developing corresponding prevention strategies.

  • ·         Corporate culture (e.g., the absence of company management’s clear commitment to SOPs and standardization; double standard practices)
  • ·         Ineffective or unclear company policies (e.g., regarding schedules, costs, go around, diversion, crew duty time, etc.)
  • ·         Inadequate awareness/ knowledge of, or failure to understand the procedure, or action (e.g., quality of wording or phrasing; procedure or action being perceived as inappropriate)
  • ·         Insufficient emphasis on strict adherence to SOPs during routine training and checks.
  • ·         Insufficient vigilance (e.g., due to fatigue)
  • ·       Distractions (e.g., due to cockpit activity)
  • ·         Interruptions (e.g., due to ATC communication)
  • ·         Task saturation resulting in fixation/ degraded multi-tasking ability or task overload leading to reduced attention.
  • ·         Incorrect management of priorities (e.g., lack of or incorrect decision-making model for time-critical situations)
  • ·         Incorrect CRM techniques, especially the absence of cross-checking, crew coordination or effective backup
  • ·         Personal desires or constraints (e.g., personal schedule, press-on-itis)
  • ·         Complacency or Over confidence

An Effective SOP

An effective SOP would need the active collaboration of all stake holders, at the formulation as well as the implementation stages. The following factors should thus be considered for creating effective SOPs: -

  •  All crew members should be aware of the reasons for the procedure, and should also be convinced of the need to follow the same. It is a known fact that when flight crew members are so convinced, then they are more likely to follow the procedure, and also offer valuable feedback to improve upon an existing procedure, or  introduce a new relevant procedure.
  •   All crew members should hold the belief that the procedure is appropriate to the stated flight situation, and would cover all the likely eventualities. This should be reinforced during effective training sessions conducted by the operator’s flight instructors/ check pilots.
  •  The procedure should clearly lay down what needs to be done, by whom (PF/ PM), and when it is to be done. Each crew’s responsibilities would thus be clearly delineated.
  •  The senior supervisors should set an example through word, and more importantly through their deeds that SOPs are to be followed. Any shortcomings/ misgivings about the procedure that are pointed out by the line crew should be discussed and remedial action initiated, if considered appropriate; otherwise the crew member should be provided feedback of the reason why the suggestion is not considered worthy of implementation.

 It has been seen that many a times SOPs are not consistently implemented, in that double standards are practiced by the crew and these are also condoned by the instructors/ check pilots/ managers. Flight crews follow the SOPs during training and check rides, but do it their own way during routine line operations. When this kind of a situation exists, it is an indication that the SOP is either not practical or effective for some reason. The reason for the deviation should thus be investigated and remedial action initiated.


Safety in aviation continues to depend on good crew performance. Good crew performance, in turn, is founded on standard operating procedures that are clear, comprehensive, and readily available to the flight crew. Development of SOPs is most effective when done by collaboration, using the best resources available including the end-users themselves, the flight crew. Once developed, effective SOPs should be consistently enforced during training as well as during line operations and ineffective SOPs should be continually reviewed and renewed. Double standards should not be permitted.

Thursday, May 30, 2013


Aircraft Operations and Communications

An aircraft comes in to regular flight operations only once it has been accorded regulatory approval, the whole purpose of which is aimed at providing an error free product. However, latent errors can still be present. The recent Boeing 787 battery snafu that led to the world wide fleet being grounded is a case in point. Even when the approval process ensures an error free aircraft, there are still chances of errors creeping in during regular flight operations because each individual aircraft is tended to by a large number of diverse groups. These errors can be prevented and safety & efficiency can be ensured only if all these diverse groups work as a team, which can only happen when there is adequate co-ordination between, and within, the various groups, viz. the flight crew, cabin crew, dispatch, Air Traffic Control, maintenance personnel, and others directly or indirectly connected with the safe operation of the flight. Communications is that vital link that helps in ensuring good co-ordination between all of these different agencies. Thus understanding communications is important for anyone connected with aviation, and more importantly for the flight deck crew, they being aviation’s last line of defence to prevent any mishap from happening.

Communication is a two way process, in which a message is sent out from the sender to the receiver; the receiver gives feedback; and this process continues in a loop until the same meaning is shared between the sender and the receiver. The message can be sent either verbally in the form of oral or written communications or through non verbal means like body language, gestures, postures, face & eye expressions, touch, etc. Communication is a concept that has been variously defined in text books. These definitions essentially characterise communications in terms of two basic issues, which are: -  

·         First, communication entails the transfer of information (facts, opinions, ideas, feelings, instructions, commands, etc.)  from the sender to the receiver
·         And second, communication entails the transfer of meaning from the sender to the receiver

Effective Communications

Communications are useful only when they are effective, in that the transfer of information from the sender to the receiver should lead to the same meaning being shared by each of them, at the completion of the transaction(s). This can only happen when the sender and receiver are both active participants in the process and thus entails a responsibility not only on the sender to obtain or elicit feedback in order to determine whether or not the communication was effective but also on the receiver, who is responsible to provide honest feedback. Or in other words, effective communication is a two way process, and is only effective when the desired understanding or action takes place. In the fatal Air India Express accident at Mangalore, the First Officer had thrice communicated to the Commander to go around, but no go around action was initiated by the Commander during the approach and touchdown phase. Would this communication be considered effective? In this paper we would only focus on effective communication between the flight deck crew.

Communications and Crew Resource Management

Effective communication between flight deck crew members is an essential tool for achieving technical, procedural, and also crew resource management objectives. The communication process amongst the flight deck crew fulfils many important functions. Research shows that these functions include:

·         The most obvious being the transfer of information in the form of checklists, logs, R/T, etc.
·         Interpersonal/ team relationships that are crucial in any highly effective team, primarily because humans are emotional, in addition to being rational beings
·         Working towards shaping predictable behaviour and expectations from the other crew members, through the medium of briefings and critiques
·         It helps the crew to develop a shared mental model about the location, spatial orientation, environment, aircraft systems, time and fuel; thereby enhancing situational awareness
·         It allows individual crew members to become aware of problems and to contribute effectively to the problem solving and decision-making process on the flight deck
·         It helps the efficient and effective management of the flight with optimum use of available resources, including the crew, through planning, implementing/ revising & monitoring the tasks; the environment; and the crew.

These functions are all crucial for safe and efficient flight operations and underpin the important role of communications on the flight deck. Research has shown that each message can have different content, depending on the circumstances. These circumstances could be whether we communicate face to face, or under high workload conditions, or on R/T, or through written messages or through gestures.

Face to Face Communications

In this kind of a situation, the message content is dependent just 7% on the spoken words. The major part of the message content is conveyed by the tone employed while speaking (38%); and on the non verbal aspects of communications (55%) like body language, eye & facial expressions, postures etc. The flight deck crew would encounter this situation when they come face to face on arrival at the dispatch and also during low workload periods, as in a long cruise on autopilot. It is important to remember that in such a situation, words of the sender convey very little meaning to the receiver, if they are not backed by the right tone and the non verbal cues. The message communicated during this interaction would be stored and all future interactions on the flight deck would take place keeping the sense of the stored communications in mind.

Pre-Flight Brief:  Face to face communications normally include a pre flight brief. A good pre-flight brief is very important because it effectively touches nearly every function of communications that are enumerated above. Open questions, like ‘how is this weather likely to impact our flight? Why do you think so?’ by the Commander can draw in the other crew members into giving valuable inputs that should be incorporated in the plan, if feasible. This gives the crew a sense of ownership and would also send a very positive message, which would lead to a very effective team that is motivated to optimum individual, as well as team performance. The Commander has a major role to play in setting the tone, but the crew members also need to live up to the transactional analysis dictum of ‘I am OK, you are OK’. This can only happen if the crew members believe/ are made to believe that they have an important role to play in the safe and efficient conduct of the flight. This can happen if all crew members are encouraged to participate in the communication process, and more importantly are listened to, and treated like trained professionals having a vital role to play during the flight. Operating from the adult ego state would be desirable but depending on the experience of the crew it may need to switch between the adult and the nurturing parent/ natural child ego states too, at times. Crossed and other damaging ego states should be avoided under all circumstances.

High workload situations

The contents of the message change completely in a high work load situation, like during a take-off, landing or during non normal situations. Here words convey 55% of the meaning; the tone of the words spoken another 38%, and body language just the balance 7%. This tells us that it is most important to use standard phraseology with the correct intonation and sense of urgency during these situations. Standard phraseology has the advantage of brevity with accuracy, as both the sender and receiver are on the same page instantly. This however, does not rule out the need to give feedback, read back and hear back, as appropriate. High workload situations are most prone to the use of leading questions, wherein the need for quick answers overrides all else, but these are also the situations when these are most dangerous. Leading questions under such situations are thus best avoided. The analysis of a number of aircraft accidents indicate an increasing number of leading questions leading up to the accident. Leading questions generally are an indicator of a loss of situational awareness. 

Communications on R/T, Intercom or Telephone

In such a situation the content of the message is conveyed 55% through the spoken words and the balance 45% through the intonation, speed and clarity of the spoken words. Standard phraseology is vital in this situation along with feedback, read back and hear back. In case of any disruptions in any of the messages, it is important to retransmit/ seek a clarification instead of assuming, as was the case in the tragic Tenerife accident. Choice of words in verbal communications has significant safety implications. In order to minimise potential ambiguities and other variances in aviation, there are certain standard rules regarding which words, phrases or other elements need to be used for communicating. As an example, ICAO phraseology requires that the word ‘departure’ is used instead of ‘take-off’ in all cases, except for the actual take-off itself. It also requires all clearances, heading, altitudes, runways etc. to be read-back by the crew, as also hear back by the ATC. This was introduced to enhance safety following many cases where messages were misinterpreted/ read back incorrectly.

Written communications

90% of the meaning is conveyed through words or symbols in written communications, with only the balance 10% through the tone of the message. This implies that the choice and use of words and symbols are critical in written communications, like in SOPs, checklists, let down charts, etc. This is even more so in the modern day cockpits with EFIS; the choice of symbols, colours, updating of the databases, etc. become even more critical as there is no dynamic feedback available in the cockpit that can prevent misconceptions/ misrepresentations from leading to an untoward incident. Updation date of the database should be checked before every flight by the crew to ensure that the database is current. The initiator of the written communications should be able to unambiguously create the message in such a way that clearly conveys the intended meaning. It is the responsibility of the crew also to clarify every written communication and get it rectified in case the words and symbols, etc. are perceived differently from what they are intended to convey. Latent errors in written communications are possible and should be eliminated for safe operations.


This form of communication is routinely used in aviation while marshalling an aircraft, and demands that each signal should convey a common understanding to the sender as well as the receiver. Since aviation is an international profession, all the hand signals have been standardised and should be used to prevent chances of misunderstanding. Non standard signals should be avoided.

Accent free English Language for Communications

As discussed above, words are important in almost all forms of communications barring gestures, but even more so on R/T, intercom or telephone and also during high workload situations. The message conveyed is affected by the language employed, the individual accents, pronunciation, vocabulary and grammatical styles. Investigations in to a number of accidents brought home the requirement for a common language for the flight crew in which they should be reasonably proficient to ensure effective communications. ICAO thus recommended through SARPs that language testing should be undertaken to ensure proficiency.  Indian DGCA has implemented this recommendation vide a CAR in Section 7 titled, “English for Aviation Language - Training, Assessment, Test and Certification”.   This CAR lays down the six skill areas in which the crew need to be proficient, and tested. These areas include pronunciation, structure, vocabulary, fluency, comprehension and interactions. Six levels of competency have been identified, and crew have to attain a minimum of Level 4 to operate. The aim of this requirement is to make communications possible, and effective. Crew would still come across individual variations, and should be sensitive to this fact and thus ensure that these variations do not hinder effective communications.

Communications, Workload and Situational Awareness

It is a known fact that human cognitive resources are limited and are shared between current reasoning processes and actions. Communications also consume mental resources. This fact needs to be clearly understood and internalised to ensure that one is sensitive to the workload on the flight deck before initiating/ responding to communications or before interrupting communications already underway, for some other task. We have all experienced situations wherein an increased workload tended to shorten our sentences, as also reduce their numbers, thus increasing the chances of communication errors. The most relevant example is the execution of the ‘Before take-off checklist’. Invariably this gets interrupted by the ATC that is ready to give out the departure clearance. It is best to ask the ATC to standby and complete the checklist before taking down the clearance or take down the clearance and then re-initiate the checklist from the beginning to ensure that both of these crucial tasks are not interrupted, thus making them prone to errors.

Similarly, a person absorbed in a difficult or unfamiliar task like in an emergency situation is less likely to understand what someone is saying to them. It is always best to wait until the task is completed, or stabilised before interrupting them. It is difficult to continue with a demanding task while at the same time communicating effectively. Leading questions at such times can be disastrous, as the person may respond verbally without paying attention, due to lack of mental resources available at his/ her disposal. Please be aware that under conditions of excessive workload, one of the first signs of degraded situational awareness is a loss of the ability to listen in. Since communications consume limited mental resources, to conserve on these, communications should be restricted to task oriented only during the critical phases of flight when sterile cockpit is called for. This ensures that communications are not distracting the crew during periods of anticipated high workload and helps the crew maintain situational awareness.