Well, maybe your fleet is different but straight from our systems manual. “Two dual pump units provide a high capacity jettison rate of approximately 2600 pounds per minute.” Maybe Boeing had different options available.
Well, it could be designed by Boeing.... I doubt they lost ALL comms and nav, but they probably were below the minimum required by airline standards to continue across the ocean. Losing a power bus could do it, for example if one item on the bus failed so as to put an excess load on the line and popped the breaker.
Heck - get those guys a subscription to Fore Flight (splurge for the premium offer) and let them fly off the I pad. Toss in a Sporty's PJ handheld, and good to go!!
Just think, if everything had gone right it would have been another boring flight. While it is good to have everyone home, look at the adventure they had.!!
Route specific. You can cross the Atlantic with VHF only but you have to take a route well to the north to stay within VHF range (Blue Spruce routes). All long-haul airliners will have multiple HF and VHF radios installed, though. Nearly all with have satellite-based CPDLC as well. If both of those fail, you have to ability to relay messages through other aircraft in the area on VHF as everyone is monitoring both oceanic air-to-air (123.45) and Guard. I forgot, was this a 787? The 787 has six generators (two per engine and two on the APU) so a lot of sources of power. Losing a BUS completely is relatively rare, as each BUS can be powered by multiple sources. Losing a BUS entirely usually means a rare fault (short) or failure in the BUS switching logic. I don't have any specific information on the 787, but I have flown the 767 which would have a similar design philosophy, minus the 787's improvements. The "big Boeings" (excludes the 737 and previous) have three independent navigation systems, each anchored by its own Inertial navigation unit (IRU). There are three flight management systems (FMS) which each have an independent set of data inputs (flight data computers and sources). Each FMS maintains its own position estimate and uses data from its respective IRU, GPS, and VOR/DME/LOC inputs to update its position. Each of the systems uses its own, separate power sources and each has varying levels of backup power.
I know there’s always different options that can be selected that affect weight, altitude, etc. Guess this is one of them.
I was on a AA 757 DFW-ANC in 2009 that took a long delay after returning the gate while taxiing due to an IRU failure. And DFW-ANC isn't ETOPS and all that. I only remember it because it was the beginning of my honeymoon lol
I was on a 777, CDG to IAD. We had to stop and reboot the aircraft before take off. Luckily the reboot fixed the issue.
Our 767’s were 2600 lbs initially but a change was required by Boeing for reasons I forget that reduced the rate to 1300 lbs. you can also only dump the center tank. It’s possible to be well over normal landing weight with just wing fuel. Been there and done that single engine.
We are required by Op Specs to have HF and CPDLC; we can't go unless the latter is working upon departure. I've lost it a few times and had to revert to HF which is usually a result of lost signal.
When I see a departing aircraft, I never say "Have a safe flight.", I will say "Have a boring flight." I have had a few "safe" flights that were very "exciting" to say the least.
Great find! I shared it with my son-in-law. A bit more than just “a loss of navigational capabilities”!