The What if feature has a major flaw, and should also be redesigned to calculate LATT (Latest Authorized Takeoff Time).
We need to calculate LATT, APDL not only does not do this, but the calculation of remaining time it does is incorrect.
Consider the following very typical situation. You have 2 legs. On the first leg you block 6:10. You have a 9 hr max, so you only have 2:50 remaining. The flight time is 2:05 and you estimate a 25 minute taxi in (LGA). So now you push back and start taxi and are informed that your EDCT is 1536:
This shows you LEGAL even though you ARE GOING TO GO OVER 9. Adding up the ground delay of 33 minutes (Difference between OUT and estimated OFF) plus 2:05 plus 25 equals 3:03 which puts you over 9 by 13 minutes!
Playing around a little bit more, I assumed that they extended our EDCT by a ridiculous amount, 2 hours. I changed the Estimated OFF to 17:36 and surprisingly, there was no change in the legality or the time remaining.
The only way I was able to get it to show illegal was to change the Planned flight time. This is not right, because the time between OUT and ESTIMATED OFF IS PART OF THE FLIGHT TIME.
Suggestion: Instead of having to enter ESTIMATE OFF TIME, APDL should be TELLING US what the latest legal OFF time would be (LATT). This is the info we need to make the go/no-go decision. I had this app yesterday, and I still needed to do arithmetic on a napkin, because it doesn't make this most basic calculation. Instead, it tells me I am legal, when I am clearly not. It is really very simple, and LATT applies to both max flight time and max FDP scenarios.
I hope this makes sense. The current state of the app in confusing, illogical, and incorrect. This part of the app needs to be redesigned to make it a simple LATT calculator. It should calculate LATT for both Flight time limits and FDP and tell you which one is more limiting.
We need to calculate LATT, APDL not only does not do this, but the calculation of remaining time it does is incorrect.
Consider the following very typical situation. You have 2 legs. On the first leg you block 6:10. You have a 9 hr max, so you only have 2:50 remaining. The flight time is 2:05 and you estimate a 25 minute taxi in (LGA). So now you push back and start taxi and are informed that your EDCT is 1536:
This shows you LEGAL even though you ARE GOING TO GO OVER 9. Adding up the ground delay of 33 minutes (Difference between OUT and estimated OFF) plus 2:05 plus 25 equals 3:03 which puts you over 9 by 13 minutes!
Playing around a little bit more, I assumed that they extended our EDCT by a ridiculous amount, 2 hours. I changed the Estimated OFF to 17:36 and surprisingly, there was no change in the legality or the time remaining.
The only way I was able to get it to show illegal was to change the Planned flight time. This is not right, because the time between OUT and ESTIMATED OFF IS PART OF THE FLIGHT TIME.
Suggestion: Instead of having to enter ESTIMATE OFF TIME, APDL should be TELLING US what the latest legal OFF time would be (LATT). This is the info we need to make the go/no-go decision. I had this app yesterday, and I still needed to do arithmetic on a napkin, because it doesn't make this most basic calculation. Instead, it tells me I am legal, when I am clearly not. It is really very simple, and LATT applies to both max flight time and max FDP scenarios.
I hope this makes sense. The current state of the app in confusing, illogical, and incorrect. This part of the app needs to be redesigned to make it a simple LATT calculator. It should calculate LATT for both Flight time limits and FDP and tell you which one is more limiting.
