En-route pilot requests¶
Available now.
What it does¶
Four things a pilot can ask for once airborne and talking to whichever position currently owns the aircraft (Departure, Center, or Approach): a direct routing, an altitude change, a weather deviation, or declining an outstanding instruction with "unable." Asking any of these on a frequency that isn't currently working you gets "say again" instead.
Direct-to¶
"Request direct Battle Ground" -- approved with "cleared direct Battle Ground" for any fix on your filed route, your destination STAR's entry/transition fix, or any other fix on the currently tracked route (see Route tracking); otherwise denied with "unable, Battle Ground is not on your route." Asking direct to a fix you've already passed gets a different denial instead -- "unable, Battle Ground is behind you" -- rather than clearing you backward along your own route. An approved direct-to drops any assigned heading and is read back -- get it wrong and you'll hear "negative, cleared direct Battle Ground."
A fix name speech recognition mangles is still understood. "Direct cougar" is recognized as COUGA -- case and spaces ignored, matched by its first 4-5 letters, a sound-alike, or a close spelling against every fix actually on your route or STAR, and only when exactly one of them clearly wins (never a guess between two similar idents). Reporting "proceeding direct" or "is direct cougar" once you're already cleared there gets "roger" instead of "say again the fix", and reading back "direct cougar" itself reads back as direct COUGA.
Altitude change¶
"Request higher," "request lower," or a specific "request flight level three nine zero" / "request one two thousand." "Higher"/"lower" moves you 2,000 ft from your current assignment. Approved with "climb and maintain...", "descend and maintain...", or "maintain..." (if the request resolves to your current altitude), and is read back the same way any altitude assignment is. Outside 1,000-45,000 ft, or if the request can't be parsed, you get a bare "unable" or "say again the altitude" -- and nothing changes.
Weather deviation¶
"Request deviation 20 degrees right" (or left, with or without a degree count) -- always approved: "deviation 20 degrees right approved, advise when able to proceed direct Battle Ground" (the next fix on your route or STAR), falling back to "...proceed on course" if there's no next fix to name. A deviation drops your assigned heading the same way a direct-to does, but unlike direct-to and altitude changes, a deviation is not read back.
"Unable"¶
Saying "unable" declines whatever you were just cleared for. If there's a pending readback, that instruction is rolled back to whatever stood before it, and ATC confirms what you're still on: "roger, maintain flight level three five zero," "roger, fly heading...", or, for a direct-to being taken back, "roger, resume own navigation." With nothing pending, it's just "roger."
Conformance implications¶
An approved direct-to or altitude change updates the same clearance the airborne conformance monitor checks against, so approving one immediately changes what you're expected to fly. A deviation does the same for heading, but -- since it isn't read back -- there's nothing pinning you to a specific new course beyond "proceed direct" or "on course" once you're able.
Limitations¶
- The engine doesn't yet assign headings outside of a deviation/direct-to's own bookkeeping, so there's nothing for the heading conformance rule to clear against a "resume own navigation" instruction yet.