Atlantic and EROPS procedures

[wde12 19]

16 hours ago, skelsey said:

Not really ETOPS as such -- remember that a twin must have ETOPS certification to operate more than 60 minutes from a suitable airport, which can very easily be the case over Africa and Siberia etc at night where otherwise suitable airfields may be closed.

However, in a quad you don't enter ETOPS operation until you are more than 180 minutes from a suitable airport, which is not really limiting at all over most of the globe apart from Antarctica and parts of the South Pacific. So from a legal point of view, what is an ETOPS route in a twin is not necessarily (in fact, likely not) one in a quad. In the 747 you can operate up to 180 minutes from a suitable diversion airfield with no special requirements at all.

Legal aspects aside, from an airmanship point of view on any long-range operation over remote and/or sparsely populated areas it is prudent to have some suitable diversion options planned out to cater for the eventuality of engine failure, depressurisation etc. Of particular concern in the 747 is finding airfields with runways/aprons wide enough/strong enough to bear the weight of the aircraft (especially an issue over South America).

Indeed it is generally decompression that is the most limiting scenario, and routes over high terrain (southern Turkey, Iran, Afghanistan and the Himalayas are the particular problem areas for routes from the UK to the Middle East and South East Asia) need careful consideration: obviously in the event of a decompression it is essential to get down to FL100 in the shortest possible time (i.e. before the finite supply of oxygen on board runs out), plus over the very highest terrain there may be drift-down considerations for the eventuality of an engine failure as well. Thus there are significant 'no go' areas over the highest parts of the Himalaya where it is simply impossible to meet either the oxygen or drift-down requirements (or both), and "escape routes" are planned which must be followed in the event of a decompression to get the aircraft away from the high ground and down to a lower level as soon as practicable (usually along the lines of -- if the failure occurs before point XYZ, turn round, descend to FLxx and route to XXXX airfield via such and such a route (and there may be further 'step-down' points along the route to enable descent to FL100 as the terrain becomes less of a factor) -- if the failure occurs after point XYZ, continue on-route, descend to FLXX, route via CDE, FGH etc to diversion airfield YYYY).

Of course, don't forget that all of the above is dependent on the weather/traffic/political situation at your various possible diversion fields being amenable...

There are an awful lot of things to think about and take in to consideration -- one of the things which makes long-haul flying such a fascinating pastime...!

Great info thanks. 

Again, I know it depends on a ton of factors. But your final line kind of goes to my original question. I wish I could find a source that provides a typical list of enroute alternates used. For example, the BA dispatchers that routinely put together the trans-Asian flights to VHHH etc. could probably tell you off the top of their head the alternates considered for extended operations. In other words, I look up the real flight, see if a real plan is available, and boot up FSX with that plane at the actual gate used. I wish I could figure out as much as possible the enroute alternate planning for that flight. It may simply be that the data isn't available and I have to combine my knowledge (or lack thereof :) ) with that of PFPX and see what I cam come up with. I'd prefer to step up my game though.  

 

[scandinavian13 5,192]

1 hour ago, wde12 said:

I wish I could find a source that provides a typical list of enroute alternates used.

I think this would depend on the operator, the time of day, the agreements at the potential airports, the weather, the aircraft type, and even the dispatcher.

Things you can easily consider on your own without trying to look for data that isn't really out there:

• Will the performance of the aircraft be adequate for that airport (is the runway long enough)?
• Will the weather be reasonable? This is subjective, obviously, but keep in mind, if you're in a hurry, the last thing you'd want to be doing is flying an approach to mins and potentially go missed.
• Could the time of day create a hazard to the operation?
• Are there agreements between you and the airport operator? Granted, this isn't a go/no-go call while in the air, but if you're planning on a potential diversion point, if two adequate airports are near each other, you may bias toward the one that you have an agreement with. As an example: Flying ATL-FRA and you need to divert while near Washington DC. You have other flights out of IAD, but none out of BWI. BWI may be slightly closer to you, but IAD is somewhat larger, and would likely accommodate you a bit better since your airline has an operation there.

At its base, just filter fields based on a particular runway length. Next, consider how close they are to your route, and then some of the factors above. Some random island in the Pacific may have a perfect runway, and be right on route, but can it handle 500+ passengers, and does it have adequate medical facilities?

I'm sure the various operators keep a list of approved fields, but I doubt they're public, and I doubt it's very fixed for any given period of time. Even different times of year carry changes in diversion fields out over the water given the shifts and strength of the jetstream.

[skelsey 765]

11 hours ago, wde12 said:

Great info thanks. 

Again, I know it depends on a ton of factors. But your final line kind of goes to my original question. I wish I could find a source that provides a typical list of enroute alternates used. For example, the BA dispatchers that routinely put together the trans-Asian flights to VHHH etc. could probably tell you off the top of their head the alternates considered for extended operations. In other words, I look up the real flight, see if a real plan is available, and boot up FSX with that plane at the actual gate used. I wish I could figure out as much as possible the enroute alternate planning for that flight. It may simply be that the data isn't available and I have to combine my knowledge (or lack thereof :) ) with that of PFPX and see what I cam come up with. I'd prefer to step up my game though.  

 

As Kyle says, the things to take in to account are runway length (and, as I mentioned earlier, strength) -- these two factors in particular limit the possibilities for a B747 quite a bit to start with.

Add in political/security considerations (again this will obviously depend heavily on the airline, where they are based and their own security assessments) and this will further reduce your options.

From what's left -- as Kyle says, there are commercial considerations (i.e. does the airline have locally-based staff (for instance if it is an existing destination on the airline's network) -- or, for instance, does a sister airline or fellow alliance member have a presence?), and weather.

At the planning stage, one would use "planning minima" -- in other words, if the airfield has a CATII/III approach then the forecast should be CAT I or better, if only a CAT I ILS is available then the forecast should be sufficiently good to permit a non-precision approach with the forecast ceiling at or above MDA/H, and if only a non-precision approach is available then the forecast visibility should be 1000m or more better than that required for the approach plus forecast ceiling at least 200ft above MDA/H, and finally if only a circling approach is available then the forecast needs to be at or above the circling minima. Don't forget to check the NOTAMS in case the ILS is unserviceable etc...

Once airborne, of course, all this goes out the window and you work to the actual conditions.

If you have the real flightplan to hand then en-route alternates are commonly entered in the remarks field under RALT/.

BA to HKG, SIN etc used to (when the Jumbo went there!) use places like Ankara, Baku, Kolkata, Delhi, Bangkok etc quite regularly on the flightplan.

[skelsey 765]

On 4/4/2017 at 10:40 PM, downscc said:

I found interesting in the briefing package the couple of screens showing data on reasons for diversions on ETOPS planned flights.  Most diversions are not in the ETOPS segments and most are not due to technical (engine, decompression, etc) reasons.  Most are induced by the passengers in the form of medical emergencies.

Yes, quite -- just goes to show the incredible reliability of modern jet engines (and aircraft!).