The Great SID/STAR Phraseology Fiasco (part 2)
On 14/10/2011, in View from the left seat, by Alex1
Back in February 2011 I reported in this Blog on a particularly silly state of affairs. Pilots and controllers had got used to a simple rule where ‘each clearance replaces the old’. This means that in a clearance, such as ‘cleared FL 150, 200 or below 20 miles before X’, the constraint ‘below 20 miles before X ‘ would have to be repeated in a subsequent clearance to say, FL120 to remain in force, otherwise it would be automatically cancelled. This was the case until in 2007 amendment 15 to PANS ATM (Doc 4444), which introduced a new twist. ‘New replaces Old’ was still valid, but NOT on clearances involving SIDs and STARs, when the OPPOSITE applied.
This was presumably because controllers were finding it irksome to repeat all the restrictions contained in a Standard Arrival or Departure. To be fair, it is probably true that most standard arrivals DO still require intermediate constraints to be observed as they are often terrain related. But was this a good reason to tear up the rule book? Surely a suitable phrase could have been found to replace a mouthful of level restrictions.
The immediate result of the change was widespread confusion. This may surprise ICAO, but few pilots and controllers take PANS ATM to bed with them. So it was up to individual States to communicate the changes, which they did with typical thoroughness. Result, total confusion in November 2007 when the amendment took effect. London TMA controllers, who typically cancel SID vertical restrictions on practically every departure, were running out of breath and time saying the new formula; some pilots questioned what they were to do, others merely assumed, and only some got it right. The UK CAA made several minor changes recognising that they couldn’t unilaterally turn the clock back for fear of creating even more mayhem. For a few years now, London ATC have been saying ‘Now’ to mean ‘climb and ignore the restriction in the SID’, but that isn’t totally unambiguous. It was clearly up to ICAO to sort out the mess they had created.
Fast forward to 2009 when ICAO first polled States about the difficulties they were experiencing and then accepted an offer from CANSO, the Air Nvigation Service Providers’ trade organisation, to study the problem and provide solutions. Click here to read the full article
The Great SID/STAR Phraseology Fiasco
On 24/02/2011, in View from the left seat, by Alex1
ICAO HQ, Montreal
Most of us find the workings of ICAO pretty strange. The constant repetition of States’ sovereignty, with its assumption that they actually know what they are talking about, is quaint, rather than obviously dangerous. The glacial speed of progress, with timescales measured in years for quite minor textual changes, can be exasperating, but nothing is quite as baffling to me as this extraordinary saga of the change to the SID /STAR phraseology.
It may be that there are some out there who have not come across this piece of upside down logic, so here is a quick summary. For years (since Pontius was a pilot) the basic rule concerning clearances involving a change of level, was that the new clearance cancels the old. So if the previous descent clearance was to, say, ‘FL150 level 20 miles south of X’ and the next clearance received was just ‘FL 100’, this cancels the requirement to be at FL 150 20 miles south of X. If ATC still want you to observe that restriction, they must repeat it with the new clearance. The exact wording is (note the six levels of paragraph nesting!):
Clear? You’d think so. You might also think that this was a rather important understanding. So what are to make of the following in the current version of Doc 4444, PANS ATM, Amendment 15 dated November 2007, which given ICAO’s normal pace must have been discussed for a solid three years previously?
Translated into everyday speak, this means that if you are flying a SID with say an initial cleared level of 6000ft (you can tell I am familiar with London…) and ATC clear you to FL 110, under this rule you have to maintain 6000ft, until the end of the SID profile, wherever that is, unless you are told otherwise. This is of course the opposite of what you would do at any other time. What the ATCO meant you to do was to climb immediately to FL110
Click here to read the full article
The Responsibility of Command
On 17/01/2011, in View from the left seat, by phil
The recently published report on the crash of the Polish Presidential flight to Smolensk in April last year makes very sorry reading. Not just because of the loss of life but also because of the many systemic failures it exposes. The English language version can be found here.
In this short article I don’t want to comment on all the organisational, political and diplomatic issues which this accident has highlighted. They definitely need to be resolved (and I hope they are) as we gradually leave behind the ‘baggage’ left from the mindset of the old Warsaw Pact military environment. Instead, I have been musing on the nature and responsibilities of the pilot in command.
Most of us have had the good fortune to work in organisations where there has been good regulatory oversight, clear managerial responsibilities, good standard operating procedures, and good selection and training of aircrews. But even then, the holes in the Swiss cheese can sometimes all line up. This is where the operating crew and, in particular, the pilot in command is the last line of defence.
Click here to read the full article
KLM and Aeroflot take-off from taxi-ways
On 02/03/2010, in View from the left seat, by phil
Strange as it may seem one of the more difficult things that pilots have to deal with is finding their way around airports. Despite ICAO standardisation many obvious things like airport signage are not always the same at every airport, and even if they were, airport layouts will always differ. Surprisingly, navigating the aircraft down through the descent and arrival routes, then flying the approach and landing can often be easier than trying to navigate around the taxiways after vacating the runway. Equally, after all the hassle of getting the passengers on board, completing the checklists, pushing back on time, starting engines and leaving the ramp, finding ones’ way to the runway is not always as easy as it may seem. It really is extraordinary how difficult a seemingly simple task can be!
On the aircraft I used to fly, we had no map displays – only the basic fight instruments and paper charts. We followed our progress around the taxiways as carefully as we could following the charts. But even in good conditions it was surprisingly easy to become confused or to make a mistake. Usually this was resolved very quickly by reference to the marker boards and by checking compass headings, or by asking the tower for help. But sometimes one made a wrong turning, especially in poor visibility, or when everything was covered with snow, or at an unfamiliar airport.
Click here to read the full article
Flying the Boeing 747
On 26/02/2010, in View from the left seat, by phil
I came relatively late to the Boeing 747, first flying it in 1981 long after all the early teething problems with the PW JT9D-3 engines had been solved. We had two versions of the aircraft in British Airways, the 747-100 series with the more powerful PW JT9D-7 engines and the 747-200 with RR RB211-524 engines. The -200 version had the longer range but both variants were a delight to fly.
The first 747 delivery
Previously the two jet types I had flown were the Vickers VC10 and the Boeing 707, both excellent in their way but not as magnificent as the 747. It was not just its size that made it so. In contrast to the various earlier types of jet transports, which all had some handling vices, the 747 had none. And, again, in contrast to the earlier types it had more system redundancy than any of them. The only handling vice that I could find (if it was a vice at all) was that the nose wheel could skate along the surface if one tried to turn when taxiing at too fast a speed.
Click here to read the full article
British Airways Boeing 777 Heathrow accident final report issued
On 23/02/2010, in View from the left seat, by steve
G-YMMM was executing British Airways Flight 38 Beijing-London Heathrow on 17 January 2008 when it crash landed just short of the runway at its destination airport. Several people were injured but there were no fatalities.
The UK Air Accident Investigation Branch (AAIB) has now released its final report on the accident.
The 777 was 720 feet above ground level (AGL) on final approach to Heathrow runway 27L when an un-commanded power reduction occurred first in the right then 7 seconds later in the left Trent 800 engine. The resulting loss of airspeed caused the aircraft to touch down prematurely and skidding on the grassy surface, it came to a stop near the threshold of the runway.
The cause was identified as ice in the fuel system which impeded fuel flow to both engines.
Click here to read the full article
So you think you understand… Descent.
On 21/01/2010, in View from the left seat, by Alex1
Continuing my theme that all is rarely as it seems with how aircraft work, particularly when pilots are equipped only with half truths peddled in early training. And pity the controllers who are typically left even more in the dark about such things.
Let’s think about how fast aircraft descend. The ab initio trainers pilots first encounter operate at pretty much the same weight day in, day out. The biggest change is when the instructor gets out for that nail biting first solo, but he (she?) typically accounts for less than 10% of the aircraft mass. The student, if not too terrified to notice, will appreciate a much better rate of climb, and may spot that the aircraft glides a little further than with two on board. Those trainers typically climb and descend at much the same speed which isn’t very far from their best glide or minimum drag speeds. The student doesn’t encounter really large weight changes and wide speed variations until getting into a real airliner for the first time. At some point, perhaps after the descent planning has gone badly wrong yet again, it dawns that at high speeds, light aircraft descend faster than heavy ones.
Click here to read the full article
Pilot fatigue – The views of the Flight Safety Foundation
On 25/12/2009, in View from the left seat, by pbn
The issue of fatigue in the cockpit, and outside it among maintenance personnel for example, has been on the agenda for some time now and
things were brought to a head by the Colgan Air crash in Buffalo on Feb. 12, 2009.
Predictably, the reactions are varied and range from the studied to the opportunistic. Clearly, something as complex as human fatigue can only be addressed on a scientific basis applied in the specific aviation context. Traditional ways of regulations and compliance monitoring may also need to be reviewed before they are pronounced as the solution to this very real problem.
For some airlines fatigue risk management is nothing new and they have long ago adjusted their crew scheduling and fatigue reporting practices to mitigate the risk as much as possible. For others, the task is still looming large.
Mr. William R. Voss, President and CEO of the Flight Safety Foundation gave a testimony on 1 December 2009 to the U.S. Senate Committee on Commerce, Science and Transportation’s Subcommittee on Aviation Hearing on Aviation Safety: Pilot fatigue.
He too argues for a balanced and well reasoned approach, something that is scaleable to suit both major and smaller operators and points out that some measures that do not necessarily require a regulatory approach can be implemented now. Which is not to say that there is no need for new rules that reflect the latest scientific knowledge about fatigue and the risks it entails.
You can read the full text of the testimony here.
Aircraft Operational Fuel Savings & Noise Reduction – Past and Future
On 23/11/2009, in View from the left seat, by phil
The way pilots fly their aircraft can have a significant effect on the economics, fuel consumption and environmental performance of their airline. Many airlines and Air Navigation Service Providers are working on Constant Descent Approaches (CDAs) but to do these it is necessary to have well motivated pilots, good operating procedures and efficient ATM procedures.
Particularly on long flights, the pilots have many more things to do than just flying the aircraft. The tactical decisions they make on the day with regard to fuel load, payload, routes and altitudes, descent profiles and the deployment of flaps and landing gear can all affect the bottom line economics. In a lecture given to the Royal Aeronautical Society’s CEAS 2009 Conference last month, Captain Hugh Dibley described the work done in the past to improve operating procedures, the influence the flight crew can have over the fuel used, and some of the possible improvements in the future. In one example he showed that a fuel economy campaign and improved procedures produced savings in the order of 8%. Some recent simulation work done by SAS has shown that CDAs and optimised procedures could produce comparative savings of 18.4%. And even minor changes in operation can save at least 1% at no cost – in comparison, one engine manufacturer currently spends over £800,000,000 per year in Research and Development to improve consumption by 1%. The paper also shows how some airlines were able in the past to reduce their fuel burnt by nearly 10% virtually overnight.
Click here to read the full article
Are you sure it is better to fly high?
On 04/10/2009, in View from the left seat, by Alex1
Continuing the theme of the difference between what is commonly assumed in Aviation and the facts, let’s just think about cruise altitude. Everyone knows that aircraft fly high for reasons of efficiency, not to mention community noise. But is this always right? For years I cringed as colleagues harangued controllers, insisting that they simply had to maintain their level when ATC wanted them to descend and slow down in anticipation of holding. They didn’t need to insist. ATCOs, who to be fair have got their own problems to sort out without worrying about the flight crews’, are also largely unaware of the physics. So when is it necessary to fly high, and when doesn’t it matter?
There is no argument that for best range, aircraft need to fly high. The simplest way to look at it, is that as the altitude increases, air density decreases, and you can fly faster for the same drag. That means you get there in less time, and as jet engines’ fuel consumption is roughly proportional to thrust and time, for a given thrust, the quicker you get there the less fuel you will burn. So what stops aircraft cruising at say, FL 600? Well, this previous statement means that as the aircraft climbs into less dense air, the True Airspeed is increases, and eventually it reaches a percentage of the speed of sound (i.e. Mach Number) beyond which nasty things happen to the airflow around the aircraft.
Click here to read the full article
..and do you really understand how aircraft fly?
On 22/09/2009, in View from the left seat, by Alex1
Alice’s White Queen claimed she could believe ‘six impossible things before breakfast’. Pilots come a close second. What about that most basic bit of aeronautical knowledge, how an aeroplane flies? In the English speaking world the usual demonstration is to blow over a sheet of paper and watch it rise..
Blowing over a sheet of paper causes it to rise - but this doesn't prove that moving air is at
lower pressure than stationary.
Let’s admit it, it is impressive, and quite counter-intuitive, and there is no denying that the sheet does rise. What about the explanation? The instructor announces that this proves that ‘moving air’, i.e. the jet he has blown over the top, has lower pressure than the stationary air underneath. He then explains that the curved top surface of the wing (shows a picture of the cross section of a wing at this point) is longer than the lower surface, and so air molecules going ‘over the top’, a bit of first world war imagery there, have to travel faster to catch up with their fellows taking the shorter route. In doing so, they get further spaced out which means their pressure is reduced. Two claims, both not quite right. Of course if you blow under the sheet, it rises even more enthusiastically, but our demonstrator never shows you that. And this explanation tells us nothing about how much lift is generated.
Click here to read the full article
What have we learnt from TCAS?
On 24/08/2009, in View from the left seat, by Alex1
If there’s one sure bet in this world it is that pilots and controllers will disagree about TCAS. Controllers believe it is an invention of the devil, pilots love it, if it is u/s, they feel naked. It is a remarkable technical achievement. I remember several UK CAA briefings in the very early 80s which declared flatly that an airborne collision avoidance system was just impossible, so it was something of a surprise to find working prototypes within a few years. The first versions were very limited in their ability to adjust the advisory, and would quickly announce ‘TCAS Invalid’ if the original RA no longer suited the situation.
Pilots vetoed that, and the first operational version was vastly more capable, with the ability to upgrade, downgrade, or even reverse the advisory. Later versions improved the coordination logic. The basic collision avoidance algorithm, however, is still recognisable, based on ‘tau’ (range/range rate) criteria.
Before TCAS entry, I took part in a number of controller briefing sessions. People came up with all sorts of ingenious scenarios that they were convinced TCAS could not handle. Almost without exception TCAS passed those tests. But there is a flaw in TCAS that those controllers, and to be honest most of us working closely on the project, either ignored or under appreciated. It is the boring old problem of the human in the loop.
Click here to read the full article
Do you really understand how your trim works?
On 07/08/2009, in View from the left seat, by Alex1
Many do not, and why it matters.
Picture yourself in a conventional airliner, say a 737 of any generation. You have to do a low level go-around, perhaps because your fail passive Cat lll has just failed, er, passively. You apply GA thrust, and the aircraft pitches up. If you are low enough, you may already have some extra helpful nose up trim applied thanks to the ‘design feature’ that ensures that in the event of AP failure at low level, the aircraft pitches up not down, and so a few units of nose up trim are applied late in the approach. Your speed is low, about Vapp and the thing is pitching firmly upward. You need ample forward stick/elevator to restrain it. You don’t want to carry this load for long so you retrim. Question: if you run the trim forward while maintaining forward pressure on the wheel, what happens? Hands up all those who think the load reduces to zero. I see a lot of hands. My unscientific polling to date suggests that just about everyone is convinced that this is what happens, but it doesn’t.
Click here to read the full article
Fly on the right – A mid air mitigation
On 03/08/2009, in View from the left seat, by Alex1
On 29 September 2006, A GOL B737-800 and a private Embraer Legacy business jet collided at FL360 some 200 miles north of Brasilia, over the Amazon Jungle. The Embraer’s left winglet hit the 737’s left wing, and the 737 crashed killing all on board. The Embraer was luckier, and made a successful emergency landing at the Cachimbo air base.
Both aircraft were equipped with transponders and TCAS, so how could it have happened? But the technicalities divert attention from a vastly more important point: Was it simply bad luck that the aircraft were so close together horizontally that they collided?
Click here to read the full article
