On 24 September 2026, the Air Accidents Investigation Branch (AAIB) published its report into a serious incident involving a Boeing 737-800, registration 9H-QBD, which landed at Manchester Airport with significantly less than its final reserve fuel.
The incident occurred almost a year earlier, on 3 October 2025, during Storm Amy. The aircraft was operating a scheduled passenger flight from Pisa International Airport (ICAO: LIRP / IATA: PSA) to Glasgow Prestwick Airport (ICAO: EGPK / IATA: PIK), with 177 people on board. What followed involved three windshear escape manoeuvres, three go-arounds, two diversions and, ultimately, a fuel emergency.
For ATPL students, the report is particularly interesting because it provides a real-world case study in subjects that feature prominently in Flight Planning and Monitoring: fuel planning, alternate selection, in-flight fuel management and the protection of final reserve fuel.
The original fuel plan
The crew knew before departure that the weather could be challenging.
Storm Amy was forecast to bring strong to gale force winds, fronts and prolonged rainfall across Scotland and northern England. The operator had issued guidance reminding crews about the expected disruption and encouraged conservative fuel planning.
The operator’s standard fuel scheme required departure fuel to include taxi fuel, trip fuel, 5% contingency fuel, fuel to a destination alternate and 30 minutes of final reserve fuel. Extra fuel could also be carried for anticipated operational constraints, while the commander could add discretionary fuel.
The operational flight plan originally nominated Glasgow as the destination alternate, requiring 991 kg of alternate fuel.
Having reviewed the weather, however, the pilots decided to use Manchester instead. That increased the alternate requirement to 1,606 kg. The commander then added further discretionary fuel, resulting in a total fuel load of 11,500 kg. According to the AAIB, that additional fuel provided approximately 1 hour 12 minutes of additional flight time.
In other words, this was not a crew that had simply departed without considering the weather or the potential need to divert.
And that is what makes the incident particularly useful for students.
When the plan starts to change
The first approach to Prestwick was flown in turbulent conditions. At approximately 264 ft aal, a windshear warning activated.
The crew carried out the windshear escape manoeuvre and subsequently transitioned into a go-around.
After reviewing the fuel situation, they elected to make another approach. On the second attempt, another windshear warning occurred at approximately 50 ft aal and the crew again carried out the escape manoeuvre followed by a go-around.
At this point, the original flight plan had become something very different.
The crew intended to divert to Manchester, but ATC informed them that Manchester was unable to accept the diversion request. They therefore considered the available alternatives and requested Edinburgh.
This is where an important Flight Planning and Monitoring principle becomes very real: an alternate on a flight plan is not a guarantee that an aircraft will be able to land there.
The AAIB specifically notes that alternate aerodromes are not sent a copy of the flight plan and that a diversion has to be coordinated through ATC. Simply nominating an aerodrome as an alternate does not ensure that it will accept the aircraft.
Fuel is something you manage, not just something you calculate
Fuel planning does not end when the aircraft leaves the stand.
The AAIB report states that in-flight fuel management procedures require fuel consumption to be monitored regularly and compared with the planned consumption. The objective is to ensure that the aircraft lands with at least its final reserve fuel.
The changing fuel state of 9H-QBD demonstrates why.
At the start of the first Prestwick approach, the aircraft had 4,725 kg remaining. After the second go-around, it had 3,515 kg.
When it departed the hold to divert to Edinburgh, 2,900 kg remained.
The aircraft subsequently approached Edinburgh, where a third windshear warning occurred at 745 ft aal. The crew carried out another windshear escape manoeuvre and another go-around.
Now the situation had changed again.
Final reserve fuel is there to be protected
The aircraft’s final reserve fuel was 1,101 kg.
After the third go-around, the pilots noted that approximately 2,100 kg remained. They calculated that they required approximately 2,800 kg to divert to Manchester and land with final reserve fuel intact.
That was no longer possible.
After Manchester was entered into the flight management computer (FMC), the predicted landing fuel fell as low as 300 kg. The crew declared:
“mayday mayday mayday fuel”
and requested an immediate diversion to Manchester.
The aircraft eventually landed there with 363 kg of fuel remaining.
That figure is particularly striking when compared with the planned final reserve of 1,101 kg.
Minimum fuel and a fuel emergency are not the same thing
This incident also provides a useful opportunity to revisit terminology that ATPL students need to understand.
The report explains that minimum fuel is used to inform ATC that the available aerodrome options have been reduced to a particular intended landing aerodrome and that a change to the existing clearance could result in landing with less than the planned final reserve fuel.
Importantly, minimum fuel is not itself an emergency declaration. It tells ATC that further delay could result in an emergency.
A fuel emergency is different.
The operator’s guidance stated that when final reserve fuel could no longer be protected, a fuel emergency should be declared and available landing options explored in the interests of safety.
That distinction is much easier to appreciate when viewed in the context of an actual flight rather than as two definitions to memorise for an examination.
The alternate question
There is another detail in the report that should make Flight Planning students think.
Newcastle Airport was included among the alternates in the crew’s briefing pack. When 9H-QBD eventually diverted from Edinburgh to Manchester, Newcastle was closer and its reported wind was 290° at 22 kt.
The AAIB states that there was no consideration of using Newcastle during the diversion to Manchester.
That does not mean we should sit comfortably after the event and decide what the crew should have done. The pilots were dealing with a high-workload and rapidly developing situation following three windshear events.
It does, however, give students an excellent question to consider:
As circumstances change during a flight, are you still evaluating all of the available options?
Flight Planning and Monitoring in the real world
It is easy to think of fuel planning as a calculation performed before departure.
This incident demonstrates why the subject is called Flight Planning and Monitoring.
The plan has to be monitored because circumstances change.
Weather changes. Approaches do not always result in landings. An intended alternate may become unavailable. Holding consumes fuel. A diversion consumes fuel. A go-around consumes fuel. Another diversion changes the calculation again.
At each stage, the crew needs to know not simply how much fuel remains, but what that fuel allows them to do next.
For ATPL students studying fuel policy and the requirements around planning, replanning and in-flight fuel management, the AAIB report into 9H-QBD is therefore worth reading in full.
It demonstrates something that is easy to lose sight of when working through calculations in a question bank:
Fuel on board is a number. Fuel remaining in relation to your available options is information.
And knowing the difference is part of good flight planning.
