Northwest US to PHNL ETPs

[Spooky 1]

Are there any Hawaiin Air/NWA/ATA Boeing 767/757 pilots viewing this post that can shed some light on how you dispatch builds ETP's for flights from either KSEA/KPDX to PHNL or other island destinations? I am suspicious of some of the data I see coming from my computer generated flight planning services and wondering if on a typical KSEA to PHNL flight are using KPDX as the first half ETP airport, or are you dropping down to KSFO/KOAK as you proceed along your south westerly track towards the islands? At some point around mid ocean it would appear that KSFO would replace KPDX as the better (in time) alternate assuming winds and airport weather do not become the defining factor. For the purpose of this question I am using the Boeing "Critical Fuel Scenario" at 10,000' as outlined in AC120-42A (ETOPS). Also what kind of speeds are you using for your 10,000' diversion.

Thanks in advance. We are flying a B757 (Part 91) and although we observe many ETOPS procedures, we are not required to be an FAA approved ETOPS operator.

 

[freightdogfred]

Simple math will tell you..here is the formula

Equal time point computation----

GSR-----ETP Distance
------ = -------------
GSR+GSC--Total Distance

GSR=Ground speed return
GSC=Ground speed continue

The wind over the NoPac is far more constant in direction and velocity than the Atlantic, which is why route coordinates do not change (like the Natracks do)

Your single engine tas at 10,000 ft for the B757 you will have to plug in yourself, as I do not fly that A/C. The more accurate your wind components are calculated to adjust your ground speeds, the more accurate your ETP will really be. I routinely found more accurate ETP airports on the North Atlantic
than the dispatcher had plugged in on the computer flight plan. Mahalo!

 

[Spooky 1]

Thanks Freightdogfred. I have numbers and even have a Flight Navigator rating for all thats worth? Just looking at some of the data that continues to pop up out of the computer generated stuff that makes me curious about the accuracy of the data. In my past 121 experience we had a great group of dispatchers/meterologists that did all of these computations for us. Now that I am back in the coporate world I see some unusual stuff coming out of the lap top and would like to talk to some of the existing carriers that are transiting this piece of ocean. Your reply is appreciated though.

 

[Sleepyhead]

I'm no ETOPS expert, but I can tell you that on AQs, HNL-YVR-HNL trip, they regularly use SFO and PHTO (Hilo) for the ETP calulations.

 

[Benhuntn]

Are you using 180 mins or 120? At 180 the divert airspeed at 10m is 330 ias.

 

[HAL]

The thing to remember is that the ETP airports are based on just that point - ETP.

At some point in the flight if one of the motors conks out it will take an equal amount of time to either press on or turn back to the nearest airport behind you. Coming out of SEA most of the time our ETP airports were SFO and ITO (Hilo). Now of course earlier in the flight out of SEA PDX might have been closer, or even SEA. However the ETP airports on the flight plan is for just that one single point is space where you are an equal time forward or backward. That is a requirement put in by the FAA who love to look at the worst case scenario. At any other time if the engine goes kablooey you merely push the "nearest" button on the FMS and go there.

So a part 91 757? Would you be working for a certain former software exec & current sports team owner?

HAL

 

[Spooky 1]

Thanks for all the replys. My suspicions are confirmed with some of the data that I am getting from the computer flight plans that we see around here. I probably have at least 600+ crossings to HNL and some of the junk that you see coming out of these flight planning services is amazing.


Thanks again,

 

[Spooky 1]

Are you using 180 mins or 120? At 180 the divert airspeed at 10m is 330 ias.

As I had earlier mentioned we are not an ETOPS operator and the 60/120/180/207 minute rules really have no application to our operations. Since the west coast to Hawaii routing is probably the most strigent apploication of that concept, we cover our selves just as you would if you were flying your GV over there with the exception of the fact that we do base our ETP on a snap-shot to 10,000 feet combined with the engine loss just to make sure we always have enough fuel for the diversion.

Thanks again,