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Post by kevmul on Dec 14, 2014 13:16:26 GMT 1
I was watching a diversion this morning and started wondering about what are the thought processes when an aircraft decides to divert to a particular airport.
I understand that an aircraft squawking 7700 can be for many reasons - medical, technical, weather etc but the one this morning was an Air France B747 F-GITE. It was en-route to Paris when it sqauwked 7700. It was over the Atlantic about 200 miles west of the French coast approaching the Brest peninsula. The aircraft diverted to Shannon.
I just wondered why the pilots would choose there. Was it simply the closest appropriate airport?
Kev
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Post by northbynorthwest on Dec 14, 2014 16:19:12 GMT 1
I will try to answer this from the perspective of a U.S. carrier, where I am a Flight Dispatcher and am very involved in these decisions. We are responsible for dealing with every aspect of the flight from planning the flight until it has arrived at the gate. We and the crews work together to jointly make decisions, and I have a lot of tools at my disposal to help make the correct decisions, 24 hours a day. A meteorology department, maintenance coordinators for each specific fleet type, Medical doctors at a U.S. medical facility to name a few. Myself and any of these experts can combine in a radio patch with any of out flights anywhere in the world via radio / satcom / hf / acars. Bottom line, for us, a diversion will 99.999% of the time decided jointly between the crew, the flight dispatcher, and the medical doctor or other expert.
Choice of diversion airport is based on a number of factors, primarily the urgency of the situation. Some maintenance issues require landing at the nearest suitable airport. Suitable as being deemed suitable by our Flight Ops department, which will trigger the crews being provided Jeppesen approach plates for this airport. For example, if an emergency happens over the Irish Sea, and RAF Valley is right ahead of us, we cannot use it as the crews do not have approach plates....but they do for Dublin, Liverpool, Manchester.
We need to look at distance from present position, weather enroute, contacting ATC, weather and notams at the airport we are now planning to go to, how much fuel requires dumping, who handles us, what medical facilities are nearby. Quite often, these decisions are being made "on the fly", during a radio patch with the crew, so we are having to listen in and participate in the conversations as well as getting together all this required information. Workload goes through the roof at that time and we always have colleagues jumping in to help with phone calls, etc.
If it is an emergency, your aim is to land asap. If it is not an emergency, you also need to look at other factors, such as crew duty time, maintenance facilities and availability of parts (and do we have maintenance contracts in place). The aim here is to try to press on towards the destination with the aim of as quick a turn around as possible at an airport that has the required facilities to keep the flight going. Turning back to an airport behind you could lead to crew duty hours being exceeded, then you are now dealing with an extended delay / having customer service find hotels for passengers and crew, etc.
The flight mentioned by Kev - Air France - would have been dealing with the situation in exactly the same way as we would, as they and KLM both now have fully fledged Flight Dispatch departments operating under the same guidelines as U.S. carriers.
A long winded reply, but hopefully it shows just how complex the decision making can be for an enroute diversion. And I am not even going to begin to discuss the situation where you have to divert from your destination due to weather, fuel shortage, excessive holding, etc. That is a whole different can of worms!!!
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Post by kevmul on Dec 14, 2014 16:52:47 GMT 1
That's a brilliant explanation North - thank you very much!
Kev
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Post by deteulada on Dec 14, 2014 18:56:03 GMT 1
Excellent explanation nortbynorthwest.
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Post by Deleted on Dec 14, 2014 18:59:15 GMT 1
For example, if an emergency happens over the Irish Sea, and RAF Valley is right ahead of us, we cannot use it as the crews do not have approach plates....but they do for Dublin, Liverpool, Manchester. Just curious why you can't use RAF Valley as the Jeppesen approach plates are readily available..... |
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Post by Samba on Dec 14, 2014 20:38:11 GMT 1
Thanks Ian, I'm sure everyone is grateful for your first hand knowledge.
Bob.
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Post by Deleted on Dec 14, 2014 22:56:59 GMT 1
For example, if an emergency happens over the Irish Sea, and RAF Valley is right ahead of us, we cannot use it as the crews do not have approach plates....but they do for Dublin, Liverpool, Manchester. Just curious why you can't use RAF Valley as the Jeppesen approach plates are readily available..... Would Valley hold steps and baggage handling equipment for diverting airliners? It's a bit out of the way for arranging coaches or hotel accommodation, But I agree it's fine for a 'splash and dash', if that's all that's required. Excellent explanation northbynorthwest, btw. Agree on all counts |
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Post by northbynorthwest on Dec 14, 2014 23:18:37 GMT 1
For example, if an emergency happens over the Irish Sea, and RAF Valley is right ahead of us, we cannot use it as the crews do not have approach plates....but they do for Dublin, Liverpool, Manchester. Just curious why you can't use RAF Valley as the Jeppesen approach plates are readily available..... Hawker, the problem is that it isn't feasable for the crews to have all the plates and charts for every possible airport. They have binders absolutely full of charts for approved approaches and airports already with them in the flight deck. So, having select charts and approach plates available keeps it manageable. Another issue is that it would be a nightmare trying to keep updated charts for every possible option. When we migrate to the Electronic Flight Bag, that will make it easier, especially as it will include notams being updated and available to the crews too. |
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Post by ronturner on Dec 15, 2014 4:37:54 GMT 1
Whereas the Valley example highlights many reasons why a large passenger jet might not divert there, I am surprised that lack of charts figures as a reason. This stuff is available to download and is even part of the data base in most comm systems, even those found in light aircraft such as the Garmin 436 and others, and i know that many airlines have iPads full of this data in place of paper.
The iPad i am using to type this has the full data base of plates for Uk and France, for example. The one for france is updated every day, if i choose to do it.
RT.
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Post by northbynorthwest on Dec 15, 2014 16:26:33 GMT 1
Whereas the Valley example highlights many reasons why a large passenger jet might not divert there, I am surprised that lack of charts figures as a reason. This stuff is available to download and is even part of the data base in most comm systems, even those found in light aircraft such as the Garmin 436 and others, and i know that many airlines have iPads full of this data in place of paper. The iPad i am using to type this has the full data base of plates for Uk and France, for example. The one for france is updated every day, if i choose to do it. RT. Ron, it boils down to FAA certification of the system. iPads are not certified for use on the flight deck in our aircraft at this time. We are slowly moving towards an iPad based system in the (hopefully) near future. I am not privy to what the issues are, but I know there have been many glitches found during testing, particularly with the requirements for global coverage. It is a case of one step forward, two back at times. It will certainly make our lives easier. |
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