Narrative:

I became aware of 2 altitude problems in the following ways: departing roc airport runway 4, the clearance was 'maintain runway heading until 1200 then turn left 330.' (the IFR departure procedure on the airport page reads 'runway 4 maintain runway heading until 1200 before turning.) after takeoff, the first officer did not turn at 1200 but started to turn about 1800. I was not too alarmed because of the high rate of climb and the fact I was calling departure control who then gave further clearance, 'out of 3000 turn left to 270 on course.' again, the first officer did not commence turning at 3000, so I gave a command to turn, but by this time we were approaching about 3600' and he was beginning to turn. Later, discussion revealed he thought the altitudes were AGL. I was flying into abq from the north with a visibility left turn into runway 8 when the first officer made the SOP callout of of 1000'. However, the only problem (and distraction) is that we were actually at 500' above field elevation. The first officer was using the radio altimeter and the aircraft was over the canyon terrain west of the airport. Later discussion revealed he thought SOP callouts were based on the radio altimeter and he always used it. This was his first flight with me and first time learning about radio altimeter, absolute altitude and correct SOP. Our company books do not specify which altimeter to use for SOP callouts. However, reference is made to afe (above field elevation) and that the radio altimeter is used on CAT ii approachs so one can logically interpret the correct usage. I conducted an informed survey with fellow pilots and found confusion exists about MSL vs AGL altitudes and the misuse of the radio altimeter. I found that many pilots (capts and first officer's) use the altimeter as a crutch because they forget the field elevation and because it is easier to use since most airports have surrounding terrain at about the same elevation as the field elevation. Many second officer's use the radio altimeter also, especially at the 500' callout. Several pilots recalled incidents of first officer's calling out the wrong altitude by using the radio altimeter at airports such as san runway 27 and sfo runway 1. At the least, these incorrect callouts were a big distraction at the worst time. I tried to find a written reference to clarify precisely the MSL/AGL definition, however it is not readily available. The aim does not address the issue, the far refers to cruising altitudes but not to altitudes listed on approach pages, and even contact with 2 FAA sources produced unsatisfactory information. The problem is elementary to an instrument student because it is an unquestioned fact that the barometric altimeter is read directly to determine MSL altitude, but to a professional pilot trying to elucidate the present situation with an official written source, the problem becomes difficult. I found a reference in my instrument flying handbook (ea-AC 61-27B, revised 1971), page 56, under types of altitude, but it is brief. Nos charts make reference to altitudes as MSL, but commercial chart does not, eg, ord SID 8. Approach charts do not have reference to MSL or AGL, but their navigation pages refer to certain altitudes as MSL, but not all parts of the charts. Pilots know the missed approach altitudes are MSL, but are unsure on the IFR departure procedures on the airport page, and controller clrncs such as 'maintain runway heading until 1200, turn...'

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Original NASA ASRS Text

Title: CLRNC SPECIFIED TURN AT 1200'. PF WAS USING RADIO ALTIMETER AND DID NOT BEGIN TURN UNTIL 1400' MSL.

Narrative: I BECAME AWARE OF 2 ALT PROBS IN THE FOLLOWING WAYS: DEPARTING ROC ARPT RWY 4, THE CLRNC WAS 'MAINTAIN RWY HDG UNTIL 1200 THEN TURN LEFT 330.' (THE IFR DEP PROC ON THE ARPT PAGE READS 'RWY 4 MAINTAIN RWY HDG UNTIL 1200 BEFORE TURNING.) AFTER TKOF, THE F/O DID NOT TURN AT 1200 BUT STARTED TO TURN ABOUT 1800. I WAS NOT TOO ALARMED BECAUSE OF THE HIGH RATE OF CLB AND THE FACT I WAS CALLING DEP CTL WHO THEN GAVE FURTHER CLRNC, 'OUT OF 3000 TURN LEFT TO 270 ON COURSE.' AGAIN, THE F/O DID NOT COMMENCE TURNING AT 3000, SO I GAVE A COMMAND TO TURN, BUT BY THIS TIME WE WERE APCHING ABOUT 3600' AND HE WAS BEGINNING TO TURN. LATER, DISCUSSION REVEALED HE THOUGHT THE ALTS WERE AGL. I WAS FLYING INTO ABQ FROM THE N WITH A VIS LEFT TURN INTO RWY 8 WHEN THE F/O MADE THE SOP CALLOUT OF OF 1000'. HOWEVER, THE ONLY PROB (AND DISTR) IS THAT WE WERE ACTUALLY AT 500' ABOVE FIELD ELEVATION. THE F/O WAS USING THE RADIO ALTIMETER AND THE ACFT WAS OVER THE CANYON TERRAIN W OF THE ARPT. LATER DISCUSSION REVEALED HE THOUGHT SOP CALLOUTS WERE BASED ON THE RADIO ALTIMETER AND HE ALWAYS USED IT. THIS WAS HIS FIRST FLT WITH ME AND FIRST TIME LEARNING ABOUT RADIO ALTIMETER, ABSOLUTE ALT AND CORRECT SOP. OUR COMPANY BOOKS DO NOT SPECIFY WHICH ALTIMETER TO USE FOR SOP CALLOUTS. HOWEVER, REF IS MADE TO AFE (ABOVE FIELD ELEVATION) AND THAT THE RADIO ALTIMETER IS USED ON CAT II APCHS SO ONE CAN LOGICALLY INTERPRET THE CORRECT USAGE. I CONDUCTED AN INFORMED SURVEY WITH FELLOW PLTS AND FOUND CONFUSION EXISTS ABOUT MSL VS AGL ALTS AND THE MISUSE OF THE RADIO ALTIMETER. I FOUND THAT MANY PLTS (CAPTS AND F/O'S) USE THE ALTIMETER AS A CRUTCH BECAUSE THEY FORGET THE FIELD ELEVATION AND BECAUSE IT IS EASIER TO USE SINCE MOST ARPTS HAVE SURROUNDING TERRAIN AT ABOUT THE SAME ELEVATION AS THE FIELD ELEVATION. MANY S/O'S USE THE RADIO ALTIMETER ALSO, ESPECIALLY AT THE 500' CALLOUT. SEVERAL PLTS RECALLED INCIDENTS OF F/O'S CALLING OUT THE WRONG ALT BY USING THE RADIO ALTIMETER AT ARPTS SUCH AS SAN RWY 27 AND SFO RWY 1. AT THE LEAST, THESE INCORRECT CALLOUTS WERE A BIG DISTR AT THE WORST TIME. I TRIED TO FIND A WRITTEN REF TO CLARIFY PRECISELY THE MSL/AGL DEFINITION, HOWEVER IT IS NOT READILY AVAILABLE. THE AIM DOES NOT ADDRESS THE ISSUE, THE FAR REFERS TO CRUISING ALTS BUT NOT TO ALTS LISTED ON APCH PAGES, AND EVEN CONTACT WITH 2 FAA SOURCES PRODUCED UNSATISFACTORY INFO. THE PROB IS ELEMENTARY TO AN INSTRUMENT STUDENT BECAUSE IT IS AN UNQUESTIONED FACT THAT THE BAROMETRIC ALTIMETER IS READ DIRECTLY TO DETERMINE MSL ALT, BUT TO A PROFESSIONAL PLT TRYING TO ELUCIDATE THE PRESENT SITUATION WITH AN OFFICIAL WRITTEN SOURCE, THE PROB BECOMES DIFFICULT. I FOUND A REF IN MY INSTRUMENT FLYING HANDBOOK (EA-AC 61-27B, REVISED 1971), PAGE 56, UNDER TYPES OF ALT, BUT IT IS BRIEF. NOS CHARTS MAKE REF TO ALTS AS MSL, BUT COMMERCIAL CHART DOES NOT, EG, ORD SID 8. APCH CHARTS DO NOT HAVE REF TO MSL OR AGL, BUT THEIR NAVIGATION PAGES REFER TO CERTAIN ALTS AS MSL, BUT NOT ALL PARTS OF THE CHARTS. PLTS KNOW THE MISSED APCH ALTS ARE MSL, BUT ARE UNSURE ON THE IFR DEP PROCS ON THE ARPT PAGE, AND CTLR CLRNCS SUCH AS 'MAINTAIN RWY HDG UNTIL 1200, TURN...'

Data retrieved from NASA's ASRS site as of August 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.