September 2008 Archives

I have just learned how to force a test pilot into that dreaded syndrome known as PIOs (pilot induced oscillations). In simple parlance, the results of persistent overcontrolling when flying.

Apparently helicopters are just as - if not more - prone to PIOs than fixed wing aircraft, and it happened to be at a rotary wing forum that I gained some intriguing psychological insight into what makes even test pilots over-control. I find myself perversely pleased at the thought that test pilots struggle with flying sometimes, like the rest of us.

I was in Liverpool a week or so ago. No, not cruising down Penny Lane on the Magical Mystery Tour double-decker bus inspired by an intra-aural infusion of Lucy in the Sky with Diamonds. I was attending the Royal Aeronautical Society's 34th European Rotorcraft Forum, a conference top-heavy with rotary wing science and academia and rather light on helicopter manufacturers and operators.

But I still understood some of it. I think.

Especially when, among equations heavy with Greek alphabetical symbols, one lecturer provided the audience with an analogy I understood: what makes you get into the cycling equivalent of PIOs when riding a bike (I have blogged on the humble bike's connection with aviation before).

Back to rotary wing and PIOs. Picture a helicopter pilot flying a satellite guided precision approach, with the trajectory presented to him, on his LCD primary flight display, as a perspective of a generously proportioned rectangular "tunnel in the sky" leading to the landing site.

 

There's plenty of space in this tunnel, and the pilot flies down the middle of it without a twitch.

All you have to do to induce PIOs, according to experiment, is to make the "tunnel" narrow and shallow - to crowd the boundaries in on him.

The academics have a name for what's going on. When a pilot is flying a profile that doesn't put him under stress he follows a process they call "point tracking". He aims his aircraft where he wants to go, and goes there smoothly. If, on the other hand, he's given very close lateral and vertical boundaries, he stops "point tracking" and starts "boundary avoidance"; he keeps twitching away from the boundaries and ends up in a PIO. Even test pilots do this, I am delighted to hear.

The bike analogy is simple. You can easily cycle in a pretty straight line along the road and need little lateral space for your track. But if you were riding along the top of a wall, even a low one, suddenly you would stop unconsciously aiming your bike steadily at a constantly receding point ahead and start twitching frantically to avoid the edges.

Easy to understand, isn't it? Sometimes, something you've known instinctively all your life - but didn't bother to rationalise - gets explained to you.  But you still can't cycle along a wall without twitching. 

  

 

 

FlyBe's brilliant.

For the un-initiated it's a UK based regional airline that is now Europe's largest.

It breaks all the rules and makes money doing it when no-one else seems to be able to. It's increasing its profits when everyone else is seeing reductions or actual losses.

Which rules does it break? Well, it flies lots of turboprops (aah! turboprops - Bombardier Dash 8 Q400s to be precise)...

 

...and has a massive order book for more of them in an era when propellers are supposed to be uncool and to scare passengers because they are - allegedly - associated by the uneducated masses with a previous era.

Where it needs jets, it's building its fleet of Embraer 195s. No wonder it  is less worried about fuel prices than the rest with a fleet mix like that.

 

It flies out of airports in the UK that no-one else could make work for them, and which foreigners would never have heard of until FlyBe took them there direct.

If you overlay a map with all its routes from all its UK bases they form such a tight web they blot out almost all of the UK's coastline except Scotland's, and you can see practically none of northern Europe's coast either.

It has consistently hired ab-initio trainee airline pilots for years, and now, when all the others have stopped hiring anyone but a few direct-entry type-rated crew, it has just announced it is going to be the force behind the UK's first MPL (multi-crew pilot licence) course.

Denmark's Sterling Airlines and the Center Air Pilot Academy had recently created the world's first MPL line pilots but, with horrifying irony, the carrier had to make them redundant in less than a year despite their first class performance, because it was forced to close unprofitable routes and shed pilots on the traditional last-in, first-out basis. 

FlyBe is a little ray of sunshine in an almost universally gloomy air transport industry.

At Flight International's Crew Management Conference, the debate about the MPL versus the CPL will be examined from the airline's point of view by three different presenters.  

Mine is not intended to be a party-political blog but it's sure going to sound that way this time.

When a specific government decides on a course of action that is a fundamentally bad idea, and the proposed policy is also part of an established behaviour pattern that everyone associates with it, I suppose any opinion against the proposal is going to sound party-political.

Here we go then: the UK government is going to tax use of the aviation and marine radio spectrums for the first time in history. Or at least it will if it is not persuaded to think again by highly cogent argument in sufficient volume from the industry and elsewhere before the comment deadline on 30 October.

The particular behaviour pattern that everybody in the UK associates with the present Labour government led by prime minister Gordon Brown - and before him by Tony Blair with Brown at his side as chancellor of the exchequer - is the application of "stealth taxes". The UK Office of Communications (OFCOM), a government agency, says it is not proposing a tax on aviation's radio spectrum use, but a charge called an "administered incentive pricing" (AIP) scheme. To quote the Association of European Airlines' secretary general Ulrich Schulte-Strathaus, "an AIP is a euphemism for a tax". He argues that the money will disappear anonymously into government coffers and not be used to benefit aviation or research into improved spectrum use.

The radio spectrums affected for aviation include the frequencies allocated for HF, VHF and UHF radio communications by airlines, general aviation and the military; radar surveillance by airports, air navigation service providers and military aviation, navigation aids from Loran to the instrument landing system, and datalink communications ranging from automatic dependent surveillance - broadcast (ADS-B) to airborne collision avoidance systems (ACAS) and controller-pilot datalink communications (CPDLC).

OFCOM argues that "AIP is intended to apply market disciplines to the holding and use of spectrum rights, by requiring users to consider their spectrum needs in light of the AIP fees payable."

But why do other countries not choose to charge for these safety-sensitive services? 

Never mind, maybe we don't need to worry because OFCOM says: "We are inviting views on whether charities whose objective is the safety of human life in an emergency should receive a discount." Yes, but it's still a charge, and the government's coffers still benefit.

When I spoke to OFCOM they used, as a justification for extending spectrum charges to aviation and marine operations, the fact that the police and ambulance services already pay an AIP for them. That's not a justification, it's an indictment of the system. They should not be paying an AIP - the charge should be removed.

Those who use the spectrum directly for commercial purposes, like the television, radio, and telecommunications industries, should rightly be charged. Those who use it purely for ensuring safety should not.

The whole issue smells of stealth taxes, greed and immorality, and instinctively makes me wonder what service they will hit next with a money-grabbing scheme.  

 

 

From the start, the British Airways Boeing 777 crash at London Heathrow felt like a rare event - perhaps a one-off. But is it actually likely to happen again?

 

 

 

After all, like most big jets of its generation, the 777 has had a pretty trouble-free history since service entry in 1995, and aviation is now such a mature industry that, surely, there are few surprises left for the operator or air traveller? 

 

But the Heathrow accident has provided some surprises. The UK Air Accident Investigation Branch's latest interim report says ice particles in the fuel system is the only likely cause of this event, and adds that the behaviour of water in fuel below certain temperatures that are regularly experienced is an unknown quantity. The Branch explains: "When the fuel temperature reduces to approximately ‑18°C (0°F), the ice crystals adhere to each other and become larger. Below this temperature little is known about the properties of ice crystals in fuel and further research may be required to enable the aviation industry to more fully understand this behaviour." The fuel in G-YMMM's tanks was -22degC on the fateful final approach.

 

So what is the risk that an event like this will recur, perhaps with a much worse outcome? If the fuel supply restriction that caused G-YMMM to crash-land just inside Heathrow's boundary had occurred 30 seconds earlier, the aircraft might have hit a light industrial site and crossed two busy roads before coming to rest.

 

That said, there is a fair amount of evidence in the AAIB's latest interim report to show that the risk is very low and could be lowered further by the use of ice-inhibiting fuel additives widely used in military aviation. The report narrative confirms that, since every component in the aircraft's fuel system and in the engines is known beyond doubt to have performed as it should have done in terms of functionality, and that "waxing" of the fuel at that temperature would not have been an issue, ice particles or crystals clogging the fuel system is the only explanation for what happened.

 

Why it occurred on this and not on other flights is not yet completely clear, but it seems likely to have been the particular combination of a long fuel tank cold-soak at lower than usual temperatures, combined with an extended period of commanded low fuel flow until high power was demanded just before the unwanted power reduction on final approach.

 

Working with Boeing, the AAIB was able to mine data from 13,000 Rolls-Royce-powered 777 flights. Among these, they found 118 flights during which the fuel temperature profile for the whole flight was at or below that for G-YMMM's final trip, and others in which the fuel flows demanded were close to the profile for this flight, yet they did not experience any problems with fuel supply to the engines.

 

Because there was no fuel supply system component malfunction in G-YMMM, one of the AAIB's recommendations is: "The Federal Aviation Administration and the European Aviation Safety Agency should take immediate action to consider the implications of the findings of this investigation on other certificated airframe / engine combinations." That means everything flying, not just 777s.

 

Meanwhile it has taken 17.5 million flying hours and 3.9 million flights by all 777s for this one event to occur. Specifically for Trent 800-powered Boeing 777 s, they have flown 6.5 million hours and 1.4 million flights.

 

So all but exceptionally nervous fliers should be able to feel safe in the 777.