Tuesday, February 9, 2010

Was pilot error cause of YSR copter crash?

Was pilot error cause of YSR copter crash?

The crash investigation report is based on conjectures and wrong interpretations.

The pilot has been made the villain in the sequence of omissions and commissions.

The statement on Page 91, of the investigation report on the helicopter crash that killed former Andhra Pradesh Chief Minister Y. S. R. Reddy and others, best describes the quality of the report: ‘Useful and effective investigation techniques — nil'.

The main thrust of an accident investigation should be to identify the cause, present a conclusion and suggest recommendations to prevent a further occurrence.

The most important aspect is to keep it precise and brief. A movie script, on the other hand, may be elaborate and fictional/imaginary.

The YSR crash enquiry report seems to have taken a leaf out of the recent controversy regarding credits and acknowledgements of a Bollywood blockbuster. The report ends with seven pages of acknowledgements.

DGCA accountability

The pilot has been made the villain in the sequence of omissions and commissions. The report highlights the common errors in three recent helicopter accidents and has identified that bad weather is a common factor in all of them. What should have been the main finding is the fact that the licence of the pilot was endorsed by the DGCA without the mandatory requirements being met.

The report has also identified that certain aspects did not make the helicopter airworthy. The quality of the safety audit conducted by the DGCA has also been questioned. No one in the DGCA has been made accountable for these violations.

In the crucial moments before the fatal crash, there were clear indications that the crew were trying to keep the ground in contact and they were clearly in clouds, a situation which is not permitted in ‘Visual Flight Rules' (VFR) conditions.

Their lack of familiarity with the terrain as well as the use of GPS is also clearly indicated when the pilot talked about crossing river Krishna when they had already crossed it. The crew would not have maintained their assigned altitude of 5,500 ft and they had clearly descended to a much lower level to keep the ground visual.

The report is based on conjectures and wrong interpretations. The helicopter did not have a Digital Flight Data Recorder. The investigators should know that their conjecture of a descent rate of 14,000 ft per minute based on a pressure read out in the Engine Control Unit cannot be used as a definite tool.

Flight path

Page 7 of the report has the following significant points:

a) Examination of the wreckage site revealed that the helicopter had turned by almost ninety degrees to the left from its flight path before impact.

b) The final impact was on the slope of a hill at an altitude of 1,230 ft., where the surface is rocky.

c) The helicopter impacted the ground in steep left-nose-pitch-down attitude.

In Page 54 of the report, the indications of instruments that were recovered are mentioned. The significant indications are: a) the right side vertical speed indicator showing a rate of descent of 3,500 feet per minute and the helicopter clock had stopped at 09:29.

If the helicopter had impacted the rocky terrain with a steep nose-down attitude at 14,000 ft per minute, it would have disintegrated. No cockpit instrument or undercarriage parts would have been found intact.


The report states that the pilot-in-command could not act apparently due to incapacitation. It is obvious that the investigators are not aware of the “incapacitation procedures”. If there is no response from the pilot flying on the second call, the other pilot has to take over the controls. As there were repeated calls for ‘Go around', it cannot be assumed that there was incapacitation. The satellite imagery had indicated that the crash site was on the fringe areas of the thunderstorm clouds but it does not indicate the presence of such high downdrafts that the investigators have assumed.

Meteorological observation on September 3 indicated that rain occurred at many places in Telengana, but Kurnool reported only 0.7 cm of rain. There were no synoptic systems present exactly over the accident region. The cloud base of 600-999 metres would definitely result in the pilot getting down to a lower altitude to keep the ground visible. However, with prevailing rain conditions, it is likely that he had lost all visual perceptions.

Visual illusion

From 2001 to 2009, there have been 29 helicopter accidents, of which, 15 were fatal. A 50 per cent fatal accident rate should send shockwaves, but our system is oblivious to the danger. None of the investigation reports has addressed the dangers of visual illusions during helicopter operations — relative motion illusion and atmospheric illusion.

Relative motion illusions are common, especially when hovering over long grass or water. The downwash from the rotor disc moves the water and grass away from the aircraft.

The pilot might see water and grass seemingly moving away from him. This may be interpreted as backward movement of the helicopter, which may lead the pilot to fly forward in an attempt to maintain the hover. The result of this may be ongoing forward movement, rather than hover.

Former Speaker Balayogi's helicopter crashed into a pond. Atmospheric illusion depends on the terrain being flown/hovered over. Low-level ground operations, such as hovering or landing on areas with dust or loose grass, creates a condition called “Brown-out”.

The sudden loss of all visual cues can lead to an incident or accident.

Helicopter operators and the DGCA live with a misconception that flights can be authorised anywhere with Special VFR — visibility of 2,500 m. What they fail to note is that this is permitted only in controlled airspace.

Every helicopter flight done in clear violation of rules — without ensuring the standards of the pilots who fly them and where the quality of safety audits done by the regulator is not up to proficiency and transparency levels required — is going to endanger the lives of the passengers on board.

Strangely, in India, the political class and helicopter flights seem to follow the marriage vow, “Until death do us part”.

(The author is an airline captain with 35 years of flying experience. blfeedback@thehindu.co.in)