Air Travel – Mike's Twitter Overflow – Tech, Travel, other stuff

UK ATC Delays – a case of “Computer says No”

Many folks will have read about the ATC delays being experienced in the UK today.

Sadly, a lot of the explanations have been rather technical, not surprising since they are coming from industry experts or from those working for ATC or airlines who have a good understanding of the industry and the jargon that goes with it (e.g. “sectors”, “flow control”, “slot restrictions”, etc.).

Air Traffic Control Principles: To maintain a good margin of safety, an air traffic controller can only manage (“work“) a certain number of aircraft at the same time, taking into account the amount of communication they need to make on the radio with the planes they are working and the phase of flight those planes are in (e.g. takeoff, landing, climb, descent, cruise).

To manage the amount of traffic the UK airspace needs to handle on a daily basis, the skies are carved up into areas known as “sectors“, slotting together like a big 3D jigsaw.

Sectors: A sector handling traffic which is “in the cruise” – has taken off, finished climbing and is in level flight in the general direction of it’s destination – can generally handle more aircraft than a sector which is working traffic that is descending toward it’s destination.

For example, it takes more work to direct an aircraft to line up with the runway in order to land (several radio transmissions over 10-20 minutes), especially in the cloudy weather we get in the UK, than to tell it to fly in a straight line for 200 miles (one radio transmission in half an hour).

As an aircraft goes on it’s journey, it’s handed off from controller to controller.

The pieces of this jigsaw are set up for the “worst case scenario” – the busiest time of the day, when the most aircraft are flying in the UK and the most Air Traffic Controllers are needed on duty.

Control Positions: The consoles you see the controllers working at, which include screens with radar displays showing where the planes are, and display output which helps the controllers organise the traffic they are responsible for, make a record of their decisions, and communicate with neighbouring controllers. This includes the “telephones” and the VHF radio system for speaking to the aircraft, which are integrated into the console at the control position.

Merging sectors (Band-boxing): At night, when less planes are in the UK’s skies, the traffic is less dense, and fewer controllers are needed. These sectors are combined together, known in industry jargon as band-boxing.

The radars, radios and telephone lines for all the different sectors being combined are re-routed to the control position working the band-boxed sector. This is done using control software, and I suspect it’s this control software which has suffered a failure and become stuck in “night mode”.

It can’t “un-bandbox” the sectors, and re-route the radio and telephone lines to the right place in the control room.

The Net Effect: Because of the failure, it’s not possible to un-bandbox the merged sectors, and delegate control of the airspace to a greater number of controllers. Going back to my first point, a controller can only work a certain amount of planes while maintaining an acceptable margin of safety.

If it’s not possible to have more controllers working the traffic, they simply have to make sure there are fewer planes in the same bit of sky at the same time. To do this, ATC uses a process known as Flow Control, which consists of setting very specific (to within a few minutes) take-off times for aircraft. Because we know a plane is going to fly at a certain speed, at a requested height, along a known route, ATC can work out where a plane should be at a given time, based on it’s take-off time.

If there is too much traffic expected in the same place at the same time, ATC will work out the soonest it could safely work the traffic and then work that backward into take-off times for each plane – the slot time you hear pilots refer to.

Therefore when you hear a pilot talk about missing our slot, they don’t necessarily mean missing their time to use the runway at the departure airport, but their allotted time through some point in the air, maybe a couple of hours into the future.

Obviously, when something like this happens, the flow control and slot restrictions become more severe, also you can’t just go on delaying flights indefinitely. Airlines must also try and do their bit to reduce the strain on the available ATC resources, and they will therefore start making tactical cancellations – for instance reducing the number of flights on a given route, especially if it’s a high-frequency route with a plane every hour or two. Maybe they will cancel 50% of the flights and transfer passengers to those planes which will still operate. This frees up a slot in the airspace to be used for a flight which runs less regularly and makes sure that route is still served.

Where airlines have a fleet of planes of different sizes, so these are the larger carriers such as BA, they may try and combine two flights together on one single larger aircraft (e.g. two Airbus A319s onto a single Boeing 767). Again, this makes more space in the skies.

If you’re travelling today, I hope you get where you’re going eventually. You’ll need a lot of patience though, and resign yourself to being delayed. Sadly, being delayed is one risk you take whenever you travel, and by whatever method you choose.

If you don’t really need to make your journey today, contact your airline and offer to travel another day, they may appreciate having one less person to carry and you will release your seat for someone else that might really need it.

Latest Security Theatre: Please Remove Your Glasses

Heading back home from giving a talk at the INEX meeting in Dublin on Friday 20th September, I came across a fairly ridiculous piece of security theatre.

Welcome to Dublin Airport, by forzadagro on Flickr. — Welcome to Dublin Airport. Now remove your dignity, please.

My frequent flyer status with BA entitled me to go through the Fast-track security lane and avoid the 15-20 minute queue of glum-looking Ryanair passengers. There was a chap in front of me who had just checked in for the same BA flight.

Without seemingly flinching, the security officer supervising the loading of belongings into the x-ray machine asked the man in front to remove his spectacles and put them through the machine! I was stunned to hear this, and I think, so was he. In over 15 years of regular flying, this is the first time I’ve ever heard this be asked of someone wearing spectacles (i.e. not sunglasses worn inside). Good for him, he politely declined this seemingly random request, explaining that if he did that, he would be unable to see.

Being as blind as a bat without my glasses, I was ready to similarly decline if this security lady had any ideas about asking me to give up my glasses. Fortunately, I think she’d realised her seemingly random and possibly frivolous request had overstepped the mark, she didn’t ask me to do the same.

Now, I personally would find such a request undignified. Unable to see where I’m going clearly, I would be placed at increased risk of having an accident. It’s likely I would need to be helped through security, and helped to find my glasses once through the X-ray machine.

I don’t really see how it’s different to making a person with a prosthetic leg remove it for inspection and hop through the magnetometer arch on one leg, and I don’t see airport security guards forcing people to do that.

I put it down to poor staff training and the general ridiculousness that this security theatre is “good for us”, but I’m still pretty shocked that such a loss of dignity could even be contemplated in the first place.

I will be contacting DAA and asking them to respond and explain what their policy is regarding screening of people wearing glasses.

Third Runway, or not Third Runway?

Hot news today is Heathrow Airport’s third runway plans. It seems there’s some realisation that a “Boris Island” won’t be built early enough to satisfy the needs of the South East’s demand for landing slots, and something needs to be done now rather than in 20-odd years.

There is a perception that London lags behind Amsterdam Schiphol, Paris Charles De Gaulle or Frankfurt, in the sense that it’s not an “airline hub” of the same magnitude, and dear old London Town is being left behind.

If anyone has been through any of the above airports recently, I’m not entirely sure that being like them is something we should be aspiring to!

I’ve already made my views known about Frankfurt‘s recent redevelopments, trying to make it less painful than before, and still managing to miss the target.

Anyone who flies to Amsterdam often enough will have experienced the mind-numbingly long taxi to or from their relatively new runway, which far enough away to be built in a completely different town to the airport itself. You would be forgiven for thinking you’re driving to the UK, as the taxi time is often as long as the flight itself, unless you’re lucky enough that the prevailing wind lets you take off and land closer to the terminal.

As for Charles De Gaulle… I’ll just give you a Gallic shrug.

While Heathrow is BA’s “hub”, it’s not really a hub operation in the sense of a US air carrier. Flights don’t arrive and depart in deliberately orchestrated waves, purposely designed to connect, such as Delta’s operations in Atlanta. BA’s hub operation is more by accident, because of the sheer volume of the operation, rather than schedule design. Flights “happen” to connect, rather than do so by design.

Following the effective breakup of the BAA, Heathrow, Gatwick and Stansted are now owned by different operators, and from reading this BBC article each of them seem to be vying for a bit of the cherry, while Boris would like to demolish Heathrow entirely.

What it’s left me wondering is why there is a complete lack of joined up approach?

Danger Will Robinson! Radical thinking…

In terms of land and environmental concerns such as noise, a 2nd runway at Gatwick seems to be an easy win when compared against putting a 3rd runway at Heathrow.

Given that we’re seemingly hell bent on building HS2 (let’s ignore the fact that less than half of the money being spent on HS2 could revolutionise rail in the North of England) , wouldn’t it be eminently sensible to extend it such that it touches Heathrow and extends South to Gatwick? Use the train as a complementary form of transport to the train, rather than as a competitor.

It could then serve a dual-purpose of making it more convenient for those in the Midlands to access Heathrow and Gatwick, while also handling connecting traffic between Gatwick and Heathrow.

What would the Gatwick to Heathrow travel time be on such a train? About 20-25 minutes? I know some airports where it can take just as long to transfer between terminals, or to get from departure lounge to gate!

Might it even be possible to provide trains, or designated sections of trains, for “sterile transit” between the airports, without the need to officially enter the UK?

Yes, this will involve taking on the fearsome NIMBYs of Surrey, but isn’t it all for the “greater good”?

Should we ever decide to build “Boris Island” or devastate Hoo with a big International airport, it’s close enough to HS1 to be hooked up to that. We can offer fast train connections into Central London, and maybe even to France or Brussels from the airport. Just think, it might be preferable to fly in to Boris Island then get the train, if you’re travelling to Lille!

But, as I say, that would require some joined-up thinking. Something we need to get better at.

On a Swedish plane…

…in Sweden, in a Scandinavian published magazine, a Yorkshire-born Brit writes about British pubs, in American English (you say “crisps”, he writes “chips”, railway/railroad, po-tay-toe/po-tah-toh), and thinks that “Thame Parkway” sounds like an entry in “Jane Austen’s address book”.

I sat in my seat and cringed.

Serves me right for reading an inflight magazine, I guess.

Shine a light!

Or, go somewhere really cold and be astounded…

I’ve just come back from a fantastic weekend in Northern Sweden. Inside the Arctic Circle. Landing and taking off from a snow-covered runway at Kiruna Airport. Mostly eating reindeer.

Looking up from time to time, so I’ve been able to take amazing photos like the one above.

I’ve learned how to ride a snowmobile. I’ve also learned how to crash a snowmobile. Fortunately, landing in a couple of feet of snow is a cushioning experience, and the only bruises I came away with were to my pride, and to my wallet because a small plastic fairing got broken.

I’ve glid across deserted frozen rivers, almost silently, moved by nothing but dog power.

I’ve spent a (very chilly, -29C!) evening with top Aurora photographer Chad Blakley, picking up tips on how to get the best out of your Aurora photography, and how to set up and look after your camera in freezing conditions.

When the temperature gets down below about -15C, ice forms on any exposed hair (such as eyebrows and facial hair), up your nose, and in my case, sometimes on my glasses, as the moisture from your breath freezes.

The whole experience has been fantastic, and everyone we dealt with has been friendly, welcoming, and shared their love of the amazing area around Abisko.

We arranged the trip through Weekend a la Carte, who gave us first class advice in terms of being prepared for the Arctic, and put together a seamless experience for us.

What an amazing experience. Brilliant. Coming home to a damp 11C feels positively balmy.

First Impressions from “new” Lufthansa “Pier A” at Frankfurt

Connecting through Frankfurt, Lufthansa’s major hub, can sometimes be a fraught experience. Given that the Germans generally have a reputation for efficiency and good design, this may come as a surprise to the unseasoned traveller.

It’s something of a lottery. If you’re connecting between two flights arriving on the same gate area, then it’s easy. If not, then it’s game over. Don’t pack your running shoes – keep them handy in your hand baggage. Continue reading “First Impressions from “new” Lufthansa “Pier A” at Frankfurt”