|Quoting bristolflyer (Thread starter):|
I travelled DEN-LHR and return last week and noticed every so often a roaring noise (possible air disruption?) that would last for a minute or 2 during cruise.
1-2 minutes would be a climb to a new level, that would be about 2000'. I normally in cruise start a climb with a gentle V/S as this will gradually increase the thrust and is not as a noticeable audible change over a period of time for the passengers. Asking the aircraft to do an immediate climb will increase the thrust more rapidly. That being said, I think on the 777 there was a requirement to do full thrust step climbs after the BA
incident, not sure if that has been removed.
|Quoting jetmech (Reply 2):|
Once or twice during the flight, for a period of 10-15 seconds or so, the slipstream noise seemed to rise noticably before returning to the prior levels.
I have noticed shorter periods of cabin air conditioning noise to be associated with reducing speed, thus asking the engines to come back to idle. This changes the bleed available to the packs.
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