Blue and yellow, does anyone remember?

[dtuuri]

Looking at those altimeters reminds me how much safer the airline drum altimeters were in the 1960s.

Not sure if that's sarcasm or not. The drum altimeter may have played a role in American's Cincinnati crash in 1965 as a distracted crew, enhanced by optical illusions, descended below QFE over the Ohio River: http://www.casa.gov.au/wcmswr/_assets/main/fsa/2006/feb/40-42.pdf

"In other words, the drum presentation reverses
at below zero readings."​

I.e, instead of thinking they were below zero QFE, they could have thought they were, say, 900 feet above it.

dtuuri

 

[aterpster]

Not sure if that's sarcasm or not. The drum altimeter may have played a role in American's Cincinnati crash in 1965 as a distracted crew, enhanced by optical illusions, descended below QFE over the Ohio River: http://www.casa.gov.au/wcmswr/_assets/main/fsa/2006/feb/40-42.pdf

"In other words, the drum presentation reverses
at below zero readings."​

I.e, instead of thinking they were below zero QFE, they could have thought they were, say, 900 feet above it.

dtuuri

QFE throws a different dimension on it. My airline did not do that.

 

[Tarheelpilot]

QFE throws a different dimension on it. My airline did not do that.

I have never worked any where that used QFE nor flown international where its required so I don't have any experience using it either. Can you tell me what was so special about QFE? It just seemed to make **** a lot more complicated.

 

[RotorDude]

I have never worked any where that used QFE nor flown international where its required so I don't have any experience using it either. Can you tell me what was so special about QFE? It just seemed to make **** a lot more complicated.

QFE is the altimeter setting referenced to the destination airport being "0".
Not more complicated than the arbitrary "sea level" as reference, and for that matter, how often do we actually land on the ocean surface?
If you have QFE set in your Kollsman window, your DA on the ILS will be 200', not a meaningless 3,456' or whatever. As your wheels touch down, you'll be (roughly) at 0'. Not too bad at all, except...
This is good for one airport only, and often intended for one aircraft only, so can lead to confusion ("was that for us?")
If you lose comms, miss the approach and need to proceed to your alternate, good luck...
I am sure there are lots of other pros and cons, but in the US we ended up with a bit more complex, but general, QNH.

Edit: See Q codes on WP

 

[jsstevens]

Back to the blue & yellow, I just noticed both nav heads in the C-172 I fly most often have the blue and yellow indicators.

John

 

[roncachamp]

Back to the blue & yellow, I just noticed both nav heads in the C-172 I fly most often have the blue and yellow indicators.

The blue and yellow arcs were discontinued because the consensus was they provided no useful information. I don't agree with that. When using these indicators while flying a localizer, front or back course, the position of the needle always matched the position of the aircraft. On a front course and off course to the left, in the yellow side of the localizer, the needle will be to the right, in the yellow arc on the indicator. On a back course and off course to the right, in the yellow side of the localizer, the needle will be to the right, in the yellow arc on the indicator.

 

[kgruber]

The blue and yellow arcs were discontinued because the consensus was they provided no useful information. I don't agree with that. When using these indicators while flying a localizer, front or back course, the position of the needle always matched the position of the aircraft. On a front course and off course to the left, in the yellow side of the localizer, the needle will be to the right, in the yellow arc on the indicator. On a back course and off course to the right, in the yellow side of the localizer, the needle will be to the right, in the yellow arc on the indicator.

Exactly! Right, left, up ,down, upside down, backwards........all doesn't matter. If the needle is in the yellow, you're airplane is in the yellow.

"We're in the blue!"........................still relevant.

 

[Henning]

Exactly! Right, left, up ,down, upside down, backwards........all doesn't matter. If the needle is in the yellow, you're airplane is in the yellow.

"We're in the blue!"........................still relevant.

Wouldn't that be opposite?

 

[kgruber]

Wouldn't that be opposite?

You have keen insight into the obvious.

 

[Sluggo63]

QFE throws a different dimension on it. My airline did not do that.

We used to go to Almaty, Kazakhstan quite a bit. They used QFE meters over there. We set QNH feet and would have to do the conversions once we were below the Transition Level. It wasn't terribly difficult, but you had to be on your toes and making sure that you converted correctly. VMC... no worries. When it was IMC, the hair on the back of your neck stood up. There are a lot of tall rocks around that airport.

 

[roncachamp]

We used to go to Almaty, Kazakhstan quite a bit. They used QFE meters over there. We set QNH feet and would have to do the conversions once we were below the Transition Level. It wasn't terribly difficult, but you had to be on your toes and making sure that you converted correctly. VMC... no worries. When it was IMC, the hair on the back of your neck stood up. There are a lot of tall rocks around that airport.

What was the minimum vertical IFR separation there?

 

[RotorDude]

We used to go to Almaty, Kazakhstan quite a bit. They used QFE meters over there. We set QNH feet and would have to do the conversions once we were below the Transition Level. It wasn't terribly difficult, but you had to be on your toes and making sure that you converted correctly. VMC... no worries. When it was IMC, the hair on the back of your neck stood up. There are a lot of tall rocks around that airport.

If you set the QNH or QFE directly in length (pressure altitude) units, as opposed to pressure units, it implies you were using the "markers" on the altimeter, which we discussed earlier in this thread, and it seems that modern altimeters (in the US anyway) don't have them anymore. Unless you just convert them from length to pressure using a table, I suppose. In that case you could go directly from "meters QFE" to "inches Hg QFE" and not need those extra markers. Which was it in your case?

 

[Sluggo63]

What was the minimum vertical IFR separation there?

Hmm... good question... Are you talking vertical separation between aircraft? Not sure. Most places that use meters below the Transition Level have traffic separated by 300m (I think), which is pretty close to 1,000 feet. I'll look in the CRAR and see what it says in there.

Typically the altitudes we get in meters places (mostly just China) is in 300m increments. For instance out of Guangzhou/ZGGG (which is basically sea level), we'll typically get 900m on departure, then they'll step us up to 1200m, 2100m, 2400m, etc. But there's it's easy because it's QNH, so we can just fly with our altimeters in meters and we're good.

 

[Sluggo63]

If you set the QNH or QFE directly in length (pressure altitude) units, as opposed to pressure units, it implies you were using the "markers" on the altimeter, which we discussed earlier in this thread, and it seems that modern altimeters (in the US anyway) don't have them anymore. Unless you just convert them from length to pressure using a table, I suppose. In that case you could go directly from "meters QFE" to "inches Hg QFE" and not need those extra markers. Which was it in your case?

Yeah. At the time it was in the MD-11 (same procedures now in the 777). Below the Transition Level (FL70) we would ask for the local QNH altimeter setting, and set our altimeters to that. We would also hit the meters button to make our altimeters read feet again. They would give us an altitude to descend to in meters QFE. For example, "descend to 900m." Using the conversions chart on the Jepp chart, we would look and see that 900m converts to 5190 ft (MSL). We would set the plane to descend to 5200 ft (rounding up). The added benefit was that we could put those QNH feet altitudes in the FMS, so that would be giving us good data, also.

 

[roncachamp]

Hmm... good question... Are you talking vertical separation between aircraft? Not sure. Most places that use meters below the Transition Level have traffic separated by 300m (I think), which is pretty close to 1,000 feet. I'll look in the CRAR and see what it says in there.

Affirmative.

 

[Sluggo63]

Affirmative.

I couldn't find anything about what radar controllers use, although I suspect it's 300m. This RVSM table was the best I could do. I don't know if this was what you were looking for.

 

[Velocity173]

Lol! Kyrgyzstan. "Man A$$."

 

[Sluggo63]

Lol! Kyrgyzstan. "Man A$$."

Yup. Closed now, though... I never had the pleasure. I always got to go to "The Deed."

 

[roncachamp]

I couldn't find anything about what radar controllers use, although I suspect it's 300m. This RVSM table was the best I could do. I don't know if this was what you were looking for.

From the chart it looks like it's 1000 feet. Cruising levels are 1000 feet apart and based on pressure altitudes in feet.

 

[Sluggo63]

From the chart it looks like it's 1000 feet. Cruising levels are 1000 feet apart and based on pressure altitudes in feet.

Yup, I think that's what I remember. 1,000 feet above the Transition Altitude there, and 300m below the Transition Level.

 

[RotorDude]

Yeah. At the time it was in the MD-11 (same procedures now in the 777). Below the Transition Level (FL70) we would ask for the local QNH altimeter setting, and set our altimeters to that. We would also hit the meters button to make our altimeters read feet again. They would give us an altitude to descend to in meters QFE. For example, "descend to 900m." Using the conversions chart on the Jepp chart, we would look and see that 900m converts to 5190 ft (MSL). We would set the plane to descend to 5200 ft (rounding up). The added benefit was that we could put those QNH feet altitudes in the FMS, so that would be giving us good data, also.

Did they actually say that, exactly, or maybe "descend to 900m QFE"?
Because without that qualifier, it could easily be mistaken for 900m MSL.

 

[Sluggo63]

Did they actually say that, exactly, or maybe "descend to 900m QFE"?
Because without that qualifier, it could easily be mistaken for 900m MSL.

It's been a few years since I've flown into there, so I can't quite remember. We just knew that going into Almaty we were going to be doing the QFE meters thing. For some reason I seem to recall that they used the word "height" somewhere as a clue that it was AGL. "Descend to height 900m" or something like that. I can't be sure, though.

 

[RotorDude]

It's been a few years since I've flown into there, so I can't quite remember. We just knew that going into Almaty we were going to be doing the QFE meters thing. For some reason I seem to recall that they used the word "height" somewhere as a clue that it was AGL. "Descend to height 900m" or something like that. I can't be sure, though.

OK, that would make sense, though still scary (in IMC).
I guess nowadays with SBAS/GNSS it would be less of an issue.