Below Glideslope but on the PAPI's

A PAPI is a specific type of Visual Approach Slope Indicator. At least that's my understanding. VASI is used in the regs as a generic term for all visual systems, IIRC.

By the same logic, a VASI is a specific type of Visual Approach Slope Indicator (actually quite a few "types" of VASI come to mind) but quite separate from a Precision Approach Path Indicator.

Is there a reference showing where the regs use VASI as a "catch all" for visual glide path indicators?

-mini
 
By the same logic, a VASI is a specific type of Visual Approach Slope Indicator (actually quite a few "types" of VASI come to mind) but quite separate from a Precision Approach Path Indicator.

Is there a reference showing where the regs use VASI as a "catch all" for visual glide path indicators?

-mini

The AIM lumps them all into VGSIs...Visual Glideslope Indicators.
 
Over here, it is company policy to back up ALL visual approaches with an ILS (if it's available). If you are using an ILS you must follow the glideslope until inside the middle marker. At that point you are free to deviate to land. HOWEVER... our POI thinks differently, and with her in the jumpseat you follow the glideslope to the ground.

Man, if our POI did that, it would be a "pick your butt chewing" on some approaches since our FOM says 1000-1300 ft. So you either get tagged for going below GS or you get tagged for landing past 1300 ft but still in the TDZ.

I've done that Mt Vernon vis circle to land in DCA before. If you're not on your stuff, it can eat your lunch. The fact that 33 is a short runway doesn't help, either. In the CRJ, if your fully configured you can normally put the end of the runway half-way up the windscreen and be on a 3.0 degree decent. If you're a little off, it at least gives you a starting point to fine tune it. Not sure about the ERJ or the -700/900.
 
The AIM lumps them all into VGSIs...Visual Glideslope Indicators.
Correct. 2-1-2

(a) is VASI

(b) is PAPI

They're both visual "glideslope" indicators. They are not both "Visual Approach Slope Indicators" ("VASI").

Interestingly enough ... 91.175 also makes no mention (specifically) of a "PAPI" system.

-mini
 
FMS white needle visual 33 works good for that mt vernon approach into DCA for the CRJ pilots out there
 
FMS white needle visual 33 works good for that mt vernon approach into DCA for the CRJ pilots out there

The 2 times I've gotten it, it's been a circle to land at the last minute. I'd rather just fly it raw data than have my FO trying to plug something into the box at the last minute. YMMV, though.
 
The way I do it is load the ILS, biggy size, execute, then load the circle to 33, biggy size, but hold off executing it. Stay in white with the ILS tuned into Nav 1 so you get the blue needle for 1.

If tower clears you for 33, hit execute. If you get the straight in to 1, either do it like it is or hit cancel mod. Either way it's one button push away.

Sounds complicated written out but in actuality can be done in <10 seconds on the base vector.
 
Sounds complicated written out but in actuality can be done in <10 seconds on the base vector.

You think that's complicated... my unoffical LGA Expressway 31 box setup is

DIALS...DIALS085/RW31134..RW31

Gives a nice snowflake all the way around the turn and to the runway. However it really flipped some captains out and now the FOs tend to look at me like I'm crazy.

That said, I normally just fly the circle to 33 raw data. By the time you're over the Navy base satellite dishes you can see the VASI just fine.
 
Also, flying the snowflake MIGHT show you low on the glidepath on some runways. It gives you guidance to the threshold, not the TDZ.
 
Also, flying the snowflake MIGHT show you low on the glidepath on some runways. It gives you guidance to the threshold, not the TDZ.

Fly the snowflake until you pick up the VASI. Personally I like the snowflake on the circle to 33, I'll take any extra aids I can get on that one.
 
I don't have the facts (regs, AIM, opspecs, et. al.) memorized or in front of me.

However, here's my take on dipping below the ILS glidepath.

1) Will it cause you to go outside the parameters of a stablized approach?

2) Will the glideslope cause you to land outside the touchdown zone or place the aircraft in a precarious position? (calcapt's Quito example is perfect.)

3) Where is the performance calculated from? Is there a correction from the glideslope included? FAR 121 landing performance is a very conservative calculation.

4) How far behind and below the flight deck are the wheels closest to the dirt? For example, reaching way back to my tprop time, I remember flying the approach nose low. Obviously the nose gear was the closest to the ground. On the E145, (if I remember correctly) the deck angle was about 0 or 1 degree nose up, placing the mains just a little lower. The E170, the first jet with slats, flew a normal approach at about a 2.5 degree nose up attitude, placing the mains well below the nosegear. And, of course, now, the whale is the extreme example. While maintaining 2.5 degree nose up on a 3.0 degree glidepath, the trucks are about 50' below and about 95 or 100' aft of the flight deck. I think it was jtrain that pointed out the threshold crossing height, which was most excellent. In a typical day, do you need to be less than that?

Anyway, that's my take on it...
 
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