With a major storm heading north-easterly across the UK, the planning should have reasonably foreseen that an airport 56 miles east may also be unavailable, and should've further diverted prior to that point.
They likely used the majority of their final fuel reserve on the secondary diversion from EDI to MAN, presumably having planned to land at their alternate (EDI) around the time they reached the final fuel reserve.
Any CAA report into this, if there is one produced, is going to be interesting, because there's multiple people having made multiple decisions that led to this.
§ 91.167 Fuel requirements for flight in IFR conditions.
(a) No person may operate a civil aircraft in IFR conditions unless it carries enough fuel (considering weather reports and forecasts and weather conditions) to—
(1) Complete the flight to the first airport of intended landing;
(2) Except as provided in paragraph (b) of this section, fly from that airport to the alternate airport; and
(3) Fly after that for 45 minutes at normal cruising speed
Edit: in other comments here, it seems like Edinburgh to Manchester is a 45 minute flight. So yeah, they could easily have been outside of reserves when they did the go-around at Edinburgh and still had only 6 minutes left at Manchester.
Yes, you get "some" back, and its not negligible amount. Typical modern airliner can descend on 15-20:1, giving you over 150-200km (90-120mi) range from typical cruising altitude of 33 000 feet even with engines off. Most everyday descents are actually done by maintaining altitude as long as possible, and then iddling the engines fully for as long as clearance allows. (Ofc you then use engines as you geat nearer, because its safer to be a little low when stabilizing on approach, than a little high)
Thanks to turbofans(edited from turboprops) better efficiency + less drag at higher altitude its actually more fuel economical to command full thrust and gain altitude quickly, than slower climb, or maintaining altitude (which goes against our intuition from cars, where if you wanna get far, you never give full throttle).
But theres still some drag, so you dont get everything back, so you generally want to avoid murking in low altitudes as long as possible. Full thrust repeatedly at lowest altitudes (from failed go arounds) is the least economical part of flight, so you want to avoid those if possible. But its true that the altitude you gain is equivalent to "banking" the energy, just not all of it.
Yes, you get a lot of the energy back, BUT there is a huge problem!
Large airliners incur a LOT of additional drag to slow down while landing. Some of that is entirely intentional, some is less intentional.
It is highly preferred to deploy the landing gear before touching down. Failure to do so may lead to a hard landing and additional paperwork, so airlines do not allow the captain to exercise their own discretion.
Extending the flaps maintains lift at lower speed, and higher flap settings allow even lower speed. The highest flap setting generally also deploys leading edge slats.
If the wheels of the airliner touch down and detect the weight of the plane then spoilers kill the lift of the wings, air brakes fully deploy, as well as thrust reversers.
All of these things add drag, which uses up all that energy you've been converting.
The upshot is that each landing attempt uses a LOT of energy, and you have to use fuel to replenish that energy after every attempt.
In other words, yes you get it back, but only for one landing attempt.
It's not currently feasible to harvest it into fuel. It's (very very nearly) all lost to drag, on purpose.
So the entire climb "up", you are also wasting energy fighting the thick air. On the way back "down", that air again fights you, even though you are basically at idle thrust.
Your fuel reserves are calculated for cruise flight, so time spent doing low altitude flying is already at a disadvantage. "Two hours of reserves" is significantly less than that spent holding at a few thousand feet. Fuel efficiency while climbing is yet again dramatically worse
One of the challenges of aeronautics is the efficient disposition of the potential energy without converting it all into kinetic energy (ie speed) so that the landing happens at an optimally low speed - thus giving you a chance to brake and slow down at the end.
This is one of the multiple layers of defense that airlines employ. In theory, no one single failure should cause a major incident because of redundancies and planning. Airlines rely on the "Swiss-cheese" model of safety. Each layer has its own risks and "holes" but by layering enough layers together there should be no clear path between all of the layers. In theory this prevents major incidents and given the commercial airline's safety records I'd say it works pretty fucking well. Landing with minutes of fuel left should be exceptional. But it also shouldn't be fatal or a major risk due to the other layers of the system. ATC will move heaven and earth to land a plane low on fuel or with engine trouble safely. And everyone else in the system having 30+ minutes of extra fuel gives the space for this sort of emergency sorting.
I think this also reflects on the "efficiency" that MBA types bring to companies that they ruin. If an MBA sees a dozen landings with an extra hour of fuel, their mind starts churning at saving money. Surely an hour of extra fuel is too much and just wasted. Wasted because every extra gallon of fuel you take off with is extra weight you have to carry throughout the flight. Surely things would be more efficient if we could make sure planes only carry enough fuel to make their trip with very minimal overhead. And when everything goes perfectly according to plan, these decisions work out fine. Money is saved. Bonuses are paid. But the inevitable always happens. That's why it's called inevitable. Lives are lost. Wrists are slapped. Some people at the bottom lose their jobs. The world moves on.
It sounds to me like they tried harder at their intended destination than maybe they should have, followed by going to an alternate airport that probably wasn’t a good choice in the first place, and then having to divert to the final airport where luckily they could land in time.
I have no clue how else to think about it though.
I.e. prevent the journey from occurring if weather conditions are likely to be adverse above a certain threshold?
