[INVESTIGATING] 'power power' speed trigger wrong

Noticed that the 'power power' aural gpws warning comes on at a way too low 120kts...should be 210kts

Can you cite a source or some proof for this claim?

NATOPS FM F/A-18A/B/C/D 161353 and up (a power power warning at 120kts would be a tad too late IRL at this low altitude ;) )

DCS F-18 has taws installed, not gpws.

Isn't TAWS the generic term?

DCS F-18 has taws installed, not gpws.

Even if you are correct, I'm sure that there isn't any difference in this case.

Could you provide a track, please? We'll look into it and fix as necessary

Sure. First is the 'pull up' gpws warning (should come on >210kias) and the second is the 'power' gpws warning (should come on <210kias)

fa18_power..trk

Since it looks like (still not sure about it) the DCS Hornet is TAWS equipped, the 'power power' warning comes on correctly for the flaps AUTO case (speed <200, AoA >18)

But the warning doesn't come on at all with flaps HALF or FULL. It should come on above 8° AoA and below 200kias.

Furthermore it looks like this warning comes on only with the gear up, but the manual doesn't state that the gear position is involved.

Found some evidence to back up your claim in A1-F18AC-NFM-000 from September 2008.

Rule%201.16

Rule%201.16

Thanx for taking the time to post the manual pages :)

If I read it correctly the GPWS is a safety backup function and has to be selected by the pilot (Menu > HSI > Data > A/C).

Since the TAWS and the GPWS have different triggers, I assume that only one at a time can be active.

On the DCS Hornet you can (presently) select only TAWS and I have no idea if a GPWS is installed.

With all the different modification levels it's next to impossible to find out which one the DCS Hornet is.

TAWS is more like EGPWS which uses GPWS inputs and a terrain database to provide forward looking protection.

GPWS is an older system that works on radar altimeter, INS and configuration/air data sensors to avoid CFIT (Controlled Flight into Terrain). Usually it is always armed. On some aircraft you are able to disarm certain modes (e.g. Gear, flaps). On the F18 it appears to use GPWS inputs to a TAWS without digital terrain mode if the digital mapping database is not loaded (or possibly fitted) into the aircraft (as well as over the sea).

From Natops it does look like GPWS provides additional voice commands for Sink rates and gear not down in addition to the many TAWS commands.

I'm reading a little between the lines here based on experience because as always, NATOPS doesn't provide all of the answers as its designed for pilots and not systems engineers. You would need the manufacturers guides to realise exactly how a system is integrated and works fully.

With regard to the comments in this thread I would be very careful quoting single sentences within a system explanation. Some of the Natops grammar is quite poor (as quoted from many mil pilots incl myself). 'POWER POWER' below 210 kts for instance might simply relate to the system being armed for certain modes like sink rate and Angle of Bank detection. So a high sink rate at 220 kts doesn't trigger an aural 'POWER' command but at 209kts it will. Likewise an AOB of 50 degrees at 211 kts will not trigger a 'ROLL L/R' warning but at 209 kts it will.

Natops states 'A ″Power...Power″ warning is issued when the roll requirement conditions have not been met and adding power is the correct initial response. This occurs when the aircraft is below 200 KCAS (mynote: 210kts for AFC 253 or 292 or F/A-18 C/D aircraft), the AOA is above 8.5° with flaps HALF or FULL (or 18° AOA for flaps AUTO) and the throttle is not already at MAX.'

---NOTE: It states "when the roll requirement conditions have not been met". This could mean that you are in a banked turn with in excess of 45 AOB as well as <210kts , >8.5AOA with flaps Half or Full and the better initial response than rolling L/R in such a condition is to add power. IF you continue to ignore this advice it will then issue a PULL UP command.

Thanx for taking your time for your detailed explanation and interpretation :)

Since the 'power power' warning comes on in level flight (no roll requirement applicable) at 18°AoA, shouldn't the same warning come on with flaps half/full at 8.5° AoA?

But in this case a gear up condition would be required, otherwise you would get a 'power power' warning every time your AoA is 0.4° above the optimum approach AoA…

I'm glad that I don't have to develop the avionics for this bird!

Sorry for posting (false or questionable) bug reports, but at least sometimes they are justified ;)

Btw, it's not only grammar that can be a problem in manuals. Sometimes even system descriptions and emergency checklists are plain and simple wrong.

No apology necessary. Nothing wrong with healthy discussion hopefully leading to better clarity & ultimately correct modelling.

I must admit to reading that particular section in Natops four times before figuring it out.