The radio is crackling. You need to get through, but your calls have been stepped on multiple times. It’s so bad that the harried controller has just called, “Blocked!” and appealed for everyone to settle down.
Sure would help if you could convey a terse message about your needs and get an equally brief but meaningful response in all this confusion. Fortunately, the pilot-controller dialog allows all parties to do just that if you know the lingo.
You want to tell ATC that the clearance you accepted has placed you in turbulence bordering on severe, and you want out.
Saying “Looking for lower” (or higher) would get the job done, so when the opportunity presents itself, you pounce.
The controller replies, “I have your request.”
Where does that leave matters? At least now your message has gotten through. Whether traffic, workload, or an upcoming handoff is delaying an immediate issuance of new instructions wasn’t explained, but they’re working on it, so hang on.
With some clearances, you can tell right away that it isn’t acceptable. Reply, “Unable.” For example, a majority answered the July 12 poll question by saying that they would refuse clearance to an intersection several miles offshore when flying a single-engine aircraft.
Other instances are murkier. In the May 24 “Busting Beneath the Shelf” a pilot who filed IFR in the morning indulged a preference to remain VFR that afternoon—finding himself squeezed between a cloud deck above and a Class D airspace restriction below. That scenario prompted a reader inquiry: “What if a pilot only discovers his or her inability to comply with a clearance or instruction after they have accepted it?”
As with the turbulence, that depends on what options are available.
On Oct.5, 2012, a Piper PA24-250 Comanche encountered airframe icing at the assigned altitude over Colorado. “The pilot requested a lower altitude, but the altitude was still in clouds and the airplane continued to accumulate ice; the controller was unable to provide an even lower altitude to the pilot due to the minimum vectoring altitude,” said a National Transportation Safety Board accident summary.
The iced-up airplane’s pilot then “visually acquired the airport.” But as one problem often brings on the next, “on short final he reduced power and the airplane stalled about 105 mph.”
If you need out, don’t hesitate to speak up.