>> Dropping down to 10,000 feet could be a pressurisation issue but could be numerous other
>> issues as well.
>> The APU units can only be started below 14,000 feet so it may not be
>> a pressurisation issue.
>>
On the Airbus the APU can be started at any altitude. A battery start is forbidden above 25,000 feet, however, and it can only supply bleed air for air conditioning and engine relights below 22,500.
Useless trivia for the day. ^^
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