Night island flying

GX

Well-Known Member
Scenario:

You depart airport at 2000 local for a 4.6 hour flight to a remote island. Island has no divert. Divert is to return to origin. Any other divert results in newspapers and "international incident". Island has no NAVAID. Weather is only available by the controlling agency on the field, which cannot be contacted until inside of 200nm. Everything outside of that is non-radar, and due regard. The ASOS on the field has been known to be slightly "off", but the controllers on the field can give you accurate wx. You're flying an airplane that has dual GPS. You're 3.8 into the flight and lose one of the GPS's. What do you do and why?

Acft type: DC-8 with CFM's. Fuel is no factor (Enough for RTB, and mins.)

Ask if you need more info, obviously.
 

rframe

pǝʇɹǝʌuı
Forecast?

Fuel on board?

How long until I can talk to local controller, I must be getting pretty close to 200nm with .8 to go?

Can't think of too many reasons I wouldn't continue... I mean it's just a redundant nav failure.
 

highspeed

Well-Known Member
You have another ~3.8 of fuel to get back to dry land? You sure its even an option at this point to 180?
 

BEEF SUPREME

Well-Known Member
I'm not very experienced with regards to ETOPS. However if I had less than an hour to go I'd say it was safer to continue to the destination.

If you lost the second GPS would it be safer to fly over another 4 hours over open ocean? Put the compass on the big E or W and keep your fingers crossed? The sailor in me is cautiously optimistic (sounds like an adventure) the pilot side is all "hell nah!"

My airplane has equal time points, assuming I was 3.8 hours into the flight we would be forced to continue anyway. Not that flying to such a location would be approved (no nav aid, no wx, no alternate). Again it sounds like a fun adventure but rational planning dictates a big NO, at least for 135 ops.
 

GX

Well-Known Member
Forecast?

Fuel on board?

How long until I can talk to local controller, I must be getting pretty close to 200nm with .8 to go?

Can't think of too many reasons I wouldn't continue... I mean it's just a redundant nav failure.
Forecast is standard for the area. Clear through the day, late afternoon drizzle with 1500' cigs, clearing at night. 050SCT at ETA.

Fuel on board; enough to make the 180 and return, if necessary. Aircraft type is DC-8 with the CFM's. So.... .75, maybe?
 

GX

Well-Known Member
I'm not very experienced with regards to ETOPS. However if I had less than an hour to go I'd say it was safer to continue to the destination.

If you lost the second GPS would it be safer to fly over another 4 hours over open ocean? Put the compass on the big E or W and keep your fingers crossed? The sailor in me is cautiously optimistic (sounds like an adventure) the pilot side is all "hell nah!"

My airplane has equal time points, assuming I was 3.8 hours into the flight we would be forced to continue anyway. Not that flying to such a location would be approved (no nav aid, no wx, no alternate). Again it sounds like a fun adventure but rational planning dictates a big NO, at least for 135 ops.
No factor on ETOPS. 4 holer in this one.

The forecast is contracted from another location.... in Japan. :smoke: But never accurate. May as well be holding a finger up outside. We had been forecasted to be CAVU (with chance of pm rain) for the next 72 hours. A cyclone rolled in and shut everything down for 5 days.
 

MikeD

Administrator
Staff member
If you lost the second GPS would it be safer to fly over another 4 hours over open ocean? Put the compass on the big E or W and keep your fingers crossed? The sailor in me is cautiously optimistic (sounds like an adventure) the pilot side is all "hell nah!"
There was a time before GPS babies were created when this kind of thing was done daily, with nary a thought, and was fairly accurate. Back when pilots actually had skills, and even without a navigator onboard.
 

GX

Well-Known Member
There was a time before GPS babies were created when this kind of thing was done daily, with nary a thought, and was fairly accurate. Back when pilots actually had skills, and even without a navigator onboard.
I especially want to know your take on this scenario, please.

Also, is there a difference between INS, FMS, and GPS? Mind explaining?
 

MikeD

Administrator
Staff member
I especially want to know your take on this scenario, please.

Also, is there a difference between INS, FMS, and GPS? Mind explaining?
INS is a self-contained system. INS being a navigation system that uses regular gyros or laser gyros (known as an IRS), and an FMS is the automated display of various Nav systems. GPS is an external navigation system much like LORAN or OMEGA, but uses satellites instead of ground stations.

I thought you were referencing the B-1 coming to Diego, which faced similar circumstances in terms of setup, just not with the navigational problems. Their nearest divert, IIRC, was Bali.
 

GX

Well-Known Member
INS is a self-contained system, like an FMS is; INS being a naviation system, and an FMS being an automated display of various Nav systems. GPS is an external system much like LORAN or OMEGA, but uses satellites instead of ground stations.

I thought you were referencing the B-1 coming to Diego, which faced similar circumstances in terms of setup, just not with the navigational problems. Their nearest divert, IIRC, was Bali.
Does the FMS tie-in to the INS?

Nope. It was a scenario I faced flying back from leave. Departed Singapore at 2000, and headed to DG. Looked at my watch and knew we were about an hour out. Plane started a shallow right turn, and the Capt. came up on PA. Said he'd lost one of the Navs (not sure if it was INS, or GPS, but fairly sure he said GPS), and that we were turning around and heading back to Sing as there were no agreements in place, and there was no one to fix the plane. And then the issue of what to do with the pax....active duty service people, contractors, and 3rd country nationals.

The majority of the trip back to Sing was me talking with a pilot and a fellow controller about why they would 180.

So, we landed in Sing, got put up in a hotel, and flew back out the next morning in a 17 with webbing seats.
 

MikeD

Administrator
Staff member
Scenario:

You depart airport at 2000 local for a 4.6 hour flight to a remote island. Island has no divert. Divert is to return to origin. Any other divert results in newspapers and "international incident". Island has no NAVAID. Weather is only available by the controlling agency on the field, which cannot be contacted until inside of 200nm. Everything outside of that is non-radar, and due regard. The ASOS on the field has been known to be slightly "off", but the controllers on the field can give you accurate wx. You're flying an airplane that has dual GPS. You're 3.8 into the flight and lose one of the GPS's. What do you do and why?

Acft type: DC-8 with CFM's. Fuel is no factor (Enough for RTB, and mins.)

Ask if you need more info, obviously.
Regarding the situation, it's probably going to be dependant on the comfort of the crew in being able to make the mission happen, as well as the priority for the mission to need to happen. Combine that with what's legal for them to do in regards to company ops specs and the regs they operate under.

Apart from those items, older head crew? I could see them using the remaining GPS, depending on why the first one failed.....if it was an internal failure, well, you have another one. If it's a problem with GPS as a system, then you have other issues to consider. If you know the winds aloft, your heading, speed, distance to go......all the info the dead GPS had, and the good GPS still has; you can back up the good one with old fashioned DR. DC-8....you have and FE onboard anyway, and might just even have a Flight Navigator onboard, depending on the operation. DR is amazingly accurate if done correctly, and that with NOT knowing the winds or having to guess. If you already have that info from the GPS, most of your error is negated.

Young crew.....probably wouldn't be comfortable with this; as their experience is likely very low in that regard.
 

MikeD

Administrator
Staff member
Does the FMS tie-in to the INS?.
Yes. Or the GPS, or whatever nav system is in use. It essentially is a "navigator in a box", allowing all sorts of displays and buttons to be placed in a user-friendly and workload-reducing system, while displaying navigation and flightplan info on an EFIS or similar system. Flightplans can be programmed in, routes displayed, information garnered and computed, etc.

FMS.jpg
 

GX

Well-Known Member
Yes. Or the GPS, or whatever nav system is in use. It essentially is a "navigator in a box", allowing all sorts of displays and buttons to be placed in a user-friendly and workload-reducing system, while displaying navigation and flightplan info on the EFIS or similar system. Flightplans can be programmed in, etc.

View attachment 21246
Rummaging around in the cockpit, I know they had dual FMS's, and I would think?, GPS's tied into them.

Here's the airplane:

http://www.airliners.net/photo/Air-Transport-International/McDonnell-Douglas-DC-8-72CF/1391750/L/&sid=b67fa70c273c9a1b1365d69580132bf9
http://www.airliners.net/photo/Air-Transport-International/McDonnell-Douglas-DC-8-
72CF/2129589/L/&sid=b67fa70c273c9a1b1365d69580132bf9
 

BEEF SUPREME

Well-Known Member
There was a time before GPS babies were created when this kind of thing was done daily, with nary a thought, and was fairly accurate. Back when pilots actually had skills, and even without a navigator onboard.
Well as someone who learned celestial I agree. However, when you learn to think like a pilot in the present and consider explaining your actions to the CP or consider your opsecs, well adventure time is over.

On the other hand, one of my favorite places in SF is the memorial to those lost at sea during WW2 in the Pacific. It gives one pause. Most of the dudes were Army Aviators.
 

MikeD

Administrator
Staff member
Well as someone who learned celestial I agree. However, when you learn to think like a pilot in the present and consider explaining your actions to the CP or consider your opsecs, well adventure time is over.

On the other hand, one of my favorite places in SF is the memorial to those lost at sea during WW2 in the Pacific. It gives one pause. Most of the dudes were Army Aviators.
Thats why I specifically mentioned ops specs as a mitigating factor, then went on to describe the piloting aspect of it. Speaking on the piloting aspect of it, too many pilots of today are so dependant on global navigation systems, that they do not possess the ability to do any kind of manual navigation, or don't have the confidence to. When at one time, it was a basic skill.

Kind of sad, really.
 

N519AT

Ahh! This is how I change this!
Does the FMS tie-in to the INS?
I'd have to go look into our systems manual to make sure, but even on the Dash's FMS's we have two GPS inputs, one IRS input and two VOR/DME inputs. All cross reference each other to come up with a best computed position. Often results in ANP of .01.
 

slemers

Well-Known Member
I'd have to go look into our systems manual to make sure, but even on the Dash's FMS's we have two GPS inputs, one IRS input and two VOR/DME inputs. All cross reference each other to come up with a best computed position. Often results in ANP of .01.
It could have been a mel issue. They could safely continue to DG with one GPS system down, but wouldn't be able to depart with only one nav sytem for the return leg. Without looking at the MEL, that's just a guess. Usually the FE at supplemental carriers have A&Ps to deal with these situations(or a mechanic onboard), but who knows what they had in their fly away kit? The Captain could have made the decision on his own with the crew, but probably phone patched the company for their input too.
I plumbed on the -10 and 74 but never on the -8. Did some maintenance on them back in the stone ages before GPS though.
Slemers
 

dasleben

That's just, like, your opinion, man
I knew this had to be Diego. :D

3.8 hours into a 4.6 flight? I'd consider it safe to continue, but that's based on knowledge of my aircraft. The IRUs won't drift significantly in 0.8 hours, even without a position fix from the GPS or DME/DME. But again, I have no knowledge of the DC-8, and for them it may have been better to turn around. There is absolutely no need to jeopardize safety or put the crew in a legal situation just to complete the mission.

And sorry MikeD, I'm a young whippersnapper. ;)

Random aside since ETOPS was brought up: In my two-engine jet, if you're inside of an hour, you've already exited ETOPS. Not a factor.
 
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