Nervously stepping into the fray.... I confess I thought there was a use for both in a pilot report? Procedural controlled airspace (does it still exist with ADSB?) with step climbs and step descents. Pilot 'blocking' the following traffic should report 'Left' the level in order to allow the following guy to be cleared to the next level (or even that level?).
I do use both -
- leaving when given a "when ready, descend to xxxx" *
- left when asked to report on descent (doesn't happen often but it has) or being situation-ally aware of someone being on top of me.
Maybe it was a european thing i read doing JAA ATPLs? But leaving was good enough - as you were still there. Left was a required statement as it meant you had vacated and weren't going back?
Anyone who thinks a pilot reporting 'left' instead of 'leaving' is a safety issue needs their head read. At most you'll get a query from ATC if they misunderstand that you're turning when you're climbing/descending - but it's a report, not an instruction.
* Who can think of a more concise way to get around the verbal diarrhea that occurs going into Essendon from the north? "XXX, when ready, descent to niner thousand, QNH 1030, with a requirement to reach niner thousand by two zero Melbourne". Can't it just be an Essendon 1 arrival or something? Drives me nuts - and I only have to read it back once (or twice if recleared ) a flight.
** Heard it given to Qantas yesterday - first time for a ML arrival I've heard?