Callouts on final

[fonawah]

Hi everyone.
I hope this question makes sense. I regularly watch aviation flightdeck videos. I have noticed on some flights when on final and approaching the rwy threshold, one of the pilots (I think PNF) calls out figures such as "+5, +3, +4" and so on. I'm not sure what that means.
My guesses are either something to do with wind (or crosswind component), or something to do with the VSI, or something to do with trim settings!
Can anyone help?
Many thanks in advance
Fonawah

[DrSyn]

It relates to the target approach speed, fonawah. At commencement of final approach, taking into account various aspects of the current wind conditions, the pilots determine an increment above the weight-related Landing Reference Speed (VRef). This is then set on the ASI with a marker bug on a conventional instrument, and/or dialled up on a panel in the case of glass ASIs. It is often referred to as the bug speed.

Because approach and landing speeds are pretty critical on jets, the PF then endeavours to fly the final approach at bug speed. As part of the normal montoring process, PNF calls out deviations from that speed to assist the PF. This is particularly useful during the latter part of the approach when PF is visually acquiring his landing cues and would rather be looking out the window most of the time.

PNF calls out these deviations in the manner you have observed, "plus 5, "minus 3", etc, and will also include rate of descent, as in "800 down". Power adjustments can be made accordingly by PF without constantly having to look in and then out, as you have to do in your single-pilot ops.

Hope that helps.

[fonawah]

Thanks very much for that DrSyn. Very helpful and informative.
F