Another Boeing contradiction ... how unusual
The 733/4/5 AOM has the same entry (L.10.5) re use of Speedbrakes below 1000'RA, but then recommends speedbrakes not be used for speed reduction below 1000'
and 800'(AGL) in the FTM.
Either way I suspect this is more from a CYA position in regards to Boeing's stabilised approach criteria (1000' in IMC) - if you had to use speedbrakes on 4 mile final you couldn't
possibly be stabilised and require an immediate go-around
If in their next breath Boeing state you could be "non-stabilised" (by interpretation, not literally) prior to 500' (in VMC) and kiiiinda stabilised prior to 300' (circling approach) ... can't half tell they're somewhat concerned about crews getting excessive sink rates happening on the ILS. Yeah sure the book says: "use of speedbrakes
can result in rapid roll rates" (I find it a little sluggish actually), "use of speedbrakes with flaps extended is
not recommended", "speedbrakes
should be retracted at Flaps 15 or greater", and then "
if circumstances dictate use of speedbrakes with flaps extended, avoid high sink rates" (... well derrr) which standard does one choose?
Don't get me wrong, I'm all for a nice, smooth, stabilised approach (preferably well before 1000') and no last-minute manoeuvres from me thank-you kindly, but sometimes Mother Nature and ATC have other ideas (sorry guys I know ya under pressure and doing ya job). If it's <Vref+20 and <1000fpm under control it's still stabilised in my book.
Besides, on a slatless/flapless Vref+55 approach (or even a Flaps 15 approach) I've found them rather useful.
Oh, and thanks Blip - nicely put mate!
