EDTO question

[Kunai]

I'm fairly new to EDTO ops and I have a question regarding an operational aspect.

We have 180 minutes EDTO and I was taught that it's mainly a planning exercise. With the 180 minute range rings, do you fly outside the range rings if required? Some pilots in my organisation say YES, it's a planning exercise, you don't even need range rings on the fix pages once you are EDTO. Other pilots say NO, stay inside the 180 minute rings unless there is a safety issue etc.

[ChaseIt]

If its still within the 180min then yes, once your past your EEP only normal airmanship considerations apply.

[compressor stall]

No you cannot fly outside the 180 minute range ring (unless an emergency, although it'd be hard to imagine one). Your ops department have chosen a weight and corresponding speed to work out how far your aircraft would travel on one engine in 180 minutes in nil wind. Call this distance X. This distance X is your EDTO limit. You cannot fly further than Xnm from your EDTO Alternate.

However, on a given day, you are Xnm from your EDTO aerodrome, and to divert there there is a massive headwind and it might take you 3.5 hours to cover Xnm. This is fine.

Your colleagues are correct in that it's a planning exercise in nil wind. You could be more than 180 minutes flight time away from safety on a given day, but not more than the distance defined in your ops manual that has been determined to equate to 180 mins.

Things get a bit more complicated at higher ETDO limits but don't worry about that yet....

Just understand that a 180 minute is actually a predetermined distance range ring, not a time ring.

[Spooky 2]

Just curious what kind of training or checking you had prior to this question? Kind of pathetic to think there are different "opinions" on a subject like this. The books and rules don't lie.

[c100driver]

No you cannot fly outside the 180 minute range ring (unless an emergency, although it'd be hard to imagine one).

Good explanation CS, concise and correct, however one point that needs clarification is that you can deviate around weather even if that takes you beyond the EDTO range circle, but you must return to within the range circle ASAP once the weather has been avoided or as you quoted in an emergency the PinC can do what is required.

Beyond 180 is a whole different ball of wax!

[Localiser Established]

Thank you very much CS. One of the best EDTO explanations I have ever read. :ok:

[Microburst2002]

Where is the operational advantage of diverting to an airport which is even farther than your ETOPS alternate?

ETOPS is a planning thing, mostly. Once in flight, actual minima applies instead of ETOPS planning minima, so many airports become suitable that are closer than the nominated ETOPS alternates. And you have the non-nominated but still suitable ones. That can change your decision making in the event of a failure and set different ETPs. However, I can't see why you would chose to go to an airport farther away than the alternates, so far that it lies beyond the 180 min line (which is really far).

do you have a particular scenario in mind?