She kept the Squadron Leader updated as much as she needed to, but she preferred to keep comms chatter to a minimum when she was... Military-related terms: ... on patrol ... on station ...on a sortie ...on a shout [ British English, specifically used for search and rescue ] ... on recce/on recon [ British and American English, respectively ] General terms: ...in the air ...
airborne ...
at the controls ...flying ...in flight ...on a mission ...
doing (her) rounds ...
aloft
There might be other, more technical terms in use in the military for specific operations or missions
but I have no experience there.
aviation.stackexchange.com/users/62/Pondlife
Mostly when a pilot is busy in flying, the phrase used it in the air .
In your example, it will appear as: ...
she preferred to keep comms chatter to a minimum when she was in the air ...
aviation.stackexchange.com/users/65/Farhan
I've used the term "wheels up" before.
aviation.stackexchange.com/users/26551/Evan Krueger
Since you've had many in-atmosphere answers, here are a few for not-in-atmosphere flight: In /
On orbit Weightless Parabolic
(Usually used to say that something is above the Karman line but has not achieved orbital velocity)
Off-planet
aviation.stackexchange.com/users/354/dotancohen
Here is one more that might help... aloft
aviation.stackexchange.com/users/26549/Henry Taylor
Another option not yet mentioned, from U.S. military jargon, is in country , though this carries some contextual baggage.
It's similar to in enemy territory and might be used by, for example, a carrier pilot while in an assigned combat or patrol area.
It might contextually suggest to the reader that radio silence or strict concentration is important to the specific mission at hand.
It would be less fitting if you want to suggest to the reader that this pilot's general, personal preference is simply to avoid chit-chat in the cockpit.
There's also the phrase sterile cockpit which just means a policy of avoiding distractions in the cockpit.
This is a common phrase among pilots and would be used as in "She preferred to keep a sterile cockpit."
(Of course, these nuances will only matter to readers familiar with the jargon.
There's always a balance to be struck between impressing those who know the jargon and alienating those who don't.
Everyone understands " ...
while airborne " and pilots won't look at you funny for saying it.)
aviation.stackexchange.com/users/909/TypeIA
I'm writing a sci-fi story involving aircraft and space craft. I'm struggling to get the terminology right for referring to a pilot being 'in the air' either on a mission or a training exercise. I have a feeling there is a phrase for this but I'm struggling to think of it.  The context would be military, as in the following sentence:   She kept the Squadron Leader updated as much as she needed to, but she preferred to keep comms chatter to a minimum when she was in the air.
What would be a technical or slang term for 'in the air'?
aviation.stackexchange.com
<terminology>
aviation.stackexchange.com/questions/45247
aviation.stackexchange.com/users/26541/tommypyatt
Aloft, wheels up, on patrol, on recce, airborne and off-planer are all terms used to mean "in the air". There are many alternatives to "in the air", although there is nothing wrong with it and  it could be used in this context: "on patrol", "on station", "on a  sortie", "on  a shout", "on recce/on recon", "airborne", "at the controls", "flying", "in flight", "on a mission ", "doing (her) rounds", "aloft", "wheels up", "in country", "on orbit", "weightless", "parabolic", "off-planet".
There are many alternatives to "in the air", although there is nothing wrong with it and  it could be used in this context: "on patrol", "on station", "on a  sortie", "on  a shout", "on recce/on recon", "airborne", "at the controls", "flying", "in flight", "on a mission ", "doing (her) rounds", "aloft", "wheels up", "in country", "on orbit", "weightless", "parabolic", "off-planet".