Tired of fatigue myths

Any excitement at the title or introduction to your editorial on fatigue ("Tired of fatigue", Flight International, 15-21 June) soon dissipated when we realised that you, too, had been taken in by the operator-led myth that there is not much scientific data and little consensus where it does exist. In the UK and elsewhere we have been conducting trials and collating data since the Bader report of 1973. In addition, there is enormous consensus not only between the various scientific organisations within the European Committee on Aircrew Scheduling and Safety and the European Transport Safety Council, but from similar bodies as far afield as New Zealand. In 2001, the Defence Evaluation and Research Agency (now Qinetiq) and the UK Civil Aviation Authority produced fatigue avoidance software, SAFE, which drew upon much of this science.

Such guidance is of no interest to a minority of airlines. These are the same airlines that are least likely to recognise pilot unions, or to follow the inconvenient minutiae of industrial agreements. When dealing with their national authorities they are also the most likely to assert any literal reading of regulations that suits their commercial purposes.

In the same issue, Michael O'Leary of Ryanair, above the report of an accident in which fatigue is cited as an important factor, tells us that rules designed to minimise the impact of fatigue will serve to "limit flexibility" for the "most cosseted group of employees in the world". Is Mr O'Leary not persuasively making the case for caution and reflection when we ponder upon the matter of flight duty time regulations?

Capt Mervyn Granshaw Chairman, British Air Line Pilots Association, Hayes, Middlesex, UK Capt Evan Cullen President, Irish Air Line Pilots' Association, Dublin, Ireland

Cheaper than an accident

Michael O'Leary, Ryanair's chief executive, says the new European Union flightcrew duty time limitations (FCDT) will further limit flexibility of the "most cosseted group of employees in the world" (Flight International, 15-21 June).

Mr O'Leary's intemperate comments no doubt reflect, to a large degree, his frustration in presiding over a company where commercial fortune is presently on the wane.

Ironically, it is also a quintessential example of the need for the regulator to prescribe FCDT limitations. These minimum standards are necessary to protect the safety of crew, passengers and company assets in organisations with inadequate safety management systems and an immature corporate safety culture. Without regulatory intervention, corporate impatience for short-term commercial success and shareholder approval would almost certainly lead to flightcrew roster abuse.

It is not that pilots are cosseted; the question that the industry, shareholders and the public should be asking is why other safety-critical employees are not also protected by duty time limitations.

Safety may be expensive, but what the accountants appear not to have told Mr O'Leary is that it will always be cheaper than having an accident.

Michael Green Heathcote, New South Wales, Australia

Flawed flight display?

In your report (Flight International, 15-21 June) of the Airbus A340 incident at Johannesburg, you say that "the sidestick position indicator has two functions - for preflight control checks and to monitor sidestick input during take-off roll".

You later report that in its flight operations telex, Airbus reminds operators that the [sidestick controller] symbol "was not designed to be used during take-off rotation".

Before blaming the pilot or training, isn't this a basic flaw in the display philosophy of the primary flight display? If the pilot is required to monitor sidestick position indicator during take off roll only, shouldn't the indicator be automatically inhibited closer to rotation, say at V1? This is the time when the pilot must not use it for rotation and may very well be confused by its mere presence.

The pilot should not be distracted by unnecessary information at a critical phase of flight.

Omar Husseini Alsalam Aircraft, Riyadh, Saudi Arabia

Blunder or bad design?

The Emirates Airbus A340-300 take-off incident (Flight International, 15-21 June) looks like a human error - or so the Airbus statement would have us believe.

But what if this is another example of a design problem? Ambiguously designed instruments have featured in accidents before. Anecdotal evidence suggests such errors are only known about when they have to be reported via an event - until then the problem is invisible - as it was with computer mode settings when the Airbus A320 entered service.

The Emirates incident may be an ergonomic interface error - the design of the A340 primary flight display sees the brightly coloured, centrally focused sidestick position indicator dominate the instrument - until it disappears on leaving the ground: the crucial aircraft pitch indicator symbol is a neutral colour that is the same colour as the background display (black), and is only marked at the periphery of the user's visual assimilation field.

In flight, the aircraft indicator is obvious by default, but throw in the more visually dominant ground activated sidestick marker and the picture clouds. I suggest Airbus change the display - make the aircraft attitude marker a brighter colour. As for its statement that pilots should use external visual references - what do you do in fog, and what are instruments for?

Lance Cole Swindon, Wiltshire, UK

Past pointers

Your analysis of the US National Transportation Safety Board's (NTSB) recommendation on the American Airlines AA587 Airbus A300-600 accident is a case of looking to the past to point to the future (Flight International, 8-14 June).

The separation of an American Airlines A300-600 incident over Florida in 1997 and the 2001 AA587 crash is one of luck. The rudder travel limiter or "variable stop" is a "fixed-ratio system", meaning that the travel of the rudder and its pedal are chopped by fixed amounts as the speed increases up to Vmo. This has been used on Boeing and McDonnell Douglas aircraft.

But the difference between those aircraft and Airbus types is that they have a much larger "breakout force" - the amount of pedal force required to move the rudder and subsequent incremental force for full deflection. This equates, for AA587, to a 10kg (22lb) breakout, with 4.4kg incremental force for full travel. Each force is sensitive enough in isolation, but when combined with reduced pedal travel it is tailor-made for "stop to stop" overcontrol.

On the similarly sized fixed-ratio DC-10/MD-11, 50mm (2in) of travel and 30kg of muscle is required to achieve full deflection at the AA587 accident speed. The "ratio changer" system as used on all new-design Boeing transports since the 747 classic takes the pilot and unorthodox technique out of the equation. The ratio changer has full pedal travel throughout all flight segments, limiting rudder travel at the rudder and allowing full pedal travel to get full available deflection.

David Connolly Brussels, Belgium

Human errors

I have followed with great interest the various letters and articles that have appeared in the magazine over the years about single-engine flight in instrument meteorological conditions (IMC). What I have not seen mentioned from either those who promote it or from those who are against, is the human-error risk.

Many readers will no doubt recall the hurried forced landing/ diversion that the crew of one of the UK royal flight aircraft had to carry out some years ago because all four engines were leaking oil after a maintenance check.

Maintenance on these aircraft is at least double normal scheduled requirements. Components are changed at half life. Only one engine is worked on at a time. Even so, because of the human factor, the near disaster occurred. Murphy had struck yet again.

With a multi-engined aircraft, provided maintenance on each engine is staggered, you have the luxury of power available on the remaining engine to stay airborne. The remaining engine is then available to provide electrical power for flight instruments, navaids, flight management system, autopilot and pressurisation to keep us alive at cruise altitude.

I do not totally agree with a past British Airways chairman, who, when questioned why he always crossed the Atlantic in four- engined aircraft, replied that there were no five-engined aircraft available. I am happy with three, but never one in IMC.

Peter Gray Redhill, Surrey, UK

VTOL snag

John Hartley's "mad idea"(Flight International, 29 June-5 July) has at least one drawback. Certification of the single Pegasus-powered Harrier for military very short take-off and landing (VTOL) operations was possible because in the event of an engine failure in the hover, the aircraft fell at constant attitude and ejection was likely to be successful. To put it mildly, this would not be the case with multiple lift engines spread across the wings of an Avro RJ70 - or any other airframe.

John Farley Chichester, Sussex, UK

Source: Flight International