Narrative:

Clearance was for flight from las to lax-oasis 6 SID, hector transition as filed; maintain 15000' MSL, departure frequency 125.9 squawk. For the departure briefing I reviewed oasis 6 SID for runway 19L, 'climb on runway heading until las 3 DME then turn right to intercept and proceed via las R-211 degree to hector; maintain 15000'.' after takeoff on runway 19L, while climbing through 5000' MSL (approximately 4500 FPM rate of climb), the autothrottles began to retard. As PF, I immediately pushed the autothrottles disengage switch and asked the PNF/captain what was happening. He did not respond immediately but checked engine instruments, then looked at the legs page of the CDU. I checked it to compare our thrust at that moment to our climb thrust and began to level off. With no response from the captain and no obvious problem with the aircraft I reengaged the autothrottles, climb thrust was set, and I continued climb to 15000'. About that time, las vegas tower called to xfer us to departure. The captain acknowledged, called departure, who replied 'radar contact climb and maintain 15000'.' again the autothrottles began to retard, somewhere between 7000' and 8000' MSL. I again disengaged and asked the captain why they were doing that. He then realized that the computer was following the SID to cross 7 DME from las at or below 7000' MSL. I then looked at my DME and it was 5.2 DME and we were between 8500' and 9000' MSL. Upon review, it is clear that neither pilot saw the 7000 ft restriction at 7 DME as depicted on the SID.in fact this is the first time I can recall seeing a restriction of at or below in the climb phase of a SID. Because las vegas airport (mccarran international) is 2174' MSL, our aircraft was only 3000' AGL when the autothrottles initially pulled back. As PF, my first thought was that something was wrong with the autothrottles. Loss of any climb thrust on a climb out after takeoff is not a comfortable nor a desirable situation. My initial reaction was to maintain power and continue climb to our clearance altitude of 15000' MSL. When clearance delivery clears a flight to a certain altitude after takeoff, that is always the altitude pilots have in their minds to climb to in the departure phase. It is my opinion that the information on the crossing altitude is not in the best location on this SID. The normal references when reviewing a SID before departure is the 'takeoff' section for the particular runway, then the 'transition' section. The 7000' altitude was not mentioned on either section but in a separate 'departure' section. Perhaps this section would not have been overlooked if at least the altitude had been in bold-faced type. I believe another reason this restriction was overlooked is that this SID stresses minimum climb gradients, but then requires one point to be xed at or below. It is not consistent or logical. Also, if you look at the same airport's mead 8 SID, under the 'takeoff' section, each runway includes an altitude requirement in the description. And those altitudes are very noticeable on the depiction (note: usually when a SID is concerned with minimum climb gradients, the requirements would be to be at or above a certain altitude by a certain point). Finally, it is indeed essential for pilots to be even more vigilant than ever in this endless variation of environments and search for the unexpected within the standard instrument departure.

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Original NASA ASRS Text

Title: ACR MLG ALT DEVIATION OVERSHOT SID CROSSING RESTRICTION OUR OF LAS.

Narrative: CLRNC WAS FOR FLT FROM LAS TO LAX-OASIS 6 SID, HECTOR TRANSITION AS FILED; MAINTAIN 15000' MSL, DEP FREQ 125.9 SQUAWK. FOR THE DEP BRIEFING I REVIEWED OASIS 6 SID FOR RWY 19L, 'CLB ON RWY HDG UNTIL LAS 3 DME THEN TURN R TO INTERCEPT AND PROCEED VIA LAS R-211 DEG TO HECTOR; MAINTAIN 15000'.' AFTER TKOF ON RWY 19L, WHILE CLBING THROUGH 5000' MSL (APPROX 4500 FPM RATE OF CLB), THE AUTOTHROTTLES BEGAN TO RETARD. AS PF, I IMMEDIATELY PUSHED THE AUTOTHROTTLES DISENGAGE SWITCH AND ASKED THE PNF/CAPT WHAT WAS HAPPENING. HE DID NOT RESPOND IMMEDIATELY BUT CHKED ENG INSTRUMENTS, THEN LOOKED AT THE LEGS PAGE OF THE CDU. I CHKED IT TO COMPARE OUR THRUST AT THAT MOMENT TO OUR CLB THRUST AND BEGAN TO LEVEL OFF. WITH NO RESPONSE FROM THE CAPT AND NO OBVIOUS PROBLEM WITH THE ACFT I REENGAGED THE AUTOTHROTTLES, CLB THRUST WAS SET, AND I CONTINUED CLB TO 15000'. ABOUT THAT TIME, LAS VEGAS TWR CALLED TO XFER US TO DEP. THE CAPT ACKNOWLEDGED, CALLED DEP, WHO REPLIED 'RADAR CONTACT CLB AND MAINTAIN 15000'.' AGAIN THE AUTOTHROTTLES BEGAN TO RETARD, SOMEWHERE BTWN 7000' AND 8000' MSL. I AGAIN DISENGAGED AND ASKED THE CAPT WHY THEY WERE DOING THAT. HE THEN REALIZED THAT THE COMPUTER WAS FOLLOWING THE SID TO CROSS 7 DME FROM LAS AT OR BELOW 7000' MSL. I THEN LOOKED AT MY DME AND IT WAS 5.2 DME AND WE WERE BTWN 8500' AND 9000' MSL. UPON REVIEW, IT IS CLR THAT NEITHER PLT SAW THE 7000 FT RESTRICTION AT 7 DME AS DEPICTED ON THE SID.IN FACT THIS IS THE FIRST TIME I CAN RECALL SEEING A RESTRICTION OF AT OR BELOW IN THE CLB PHASE OF A SID. BECAUSE LAS VEGAS ARPT (MCCARRAN INTL) IS 2174' MSL, OUR ACFT WAS ONLY 3000' AGL WHEN THE AUTOTHROTTLES INITIALLY PULLED BACK. AS PF, MY FIRST THOUGHT WAS THAT SOMETHING WAS WRONG WITH THE AUTOTHROTTLES. LOSS OF ANY CLB THRUST ON A CLB OUT AFTER TKOF IS NOT A COMFORTABLE NOR A DESIRABLE SITUATION. MY INITIAL REACTION WAS TO MAINTAIN PWR AND CONTINUE CLB TO OUR CLRNC ALT OF 15000' MSL. WHEN CLRNC DELIVERY CLRS A FLT TO A CERTAIN ALT AFTER TKOF, THAT IS ALWAYS THE ALT PLTS HAVE IN THEIR MINDS TO CLB TO IN THE DEP PHASE. IT IS MY OPINION THAT THE INFO ON THE XING ALT IS NOT IN THE BEST LOCATION ON THIS SID. THE NORMAL REFERENCES WHEN REVIEWING A SID BEFORE DEP IS THE 'TKOF' SECTION FOR THE PARTICULAR RWY, THEN THE 'TRANSITION' SECTION. THE 7000' ALT WAS NOT MENTIONED ON EITHER SECTION BUT IN A SEPARATE 'DEP' SECTION. PERHAPS THIS SECTION WOULD NOT HAVE BEEN OVERLOOKED IF AT LEAST THE ALT HAD BEEN IN BOLD-FACED TYPE. I BELIEVE ANOTHER REASON THIS RESTRICTION WAS OVERLOOKED IS THAT THIS SID STRESSES MINIMUM CLB GRADIENTS, BUT THEN REQUIRES ONE POINT TO BE XED AT OR BELOW. IT IS NOT CONSISTENT OR LOGICAL. ALSO, IF YOU LOOK AT THE SAME ARPT'S MEAD 8 SID, UNDER THE 'TKOF' SECTION, EACH RWY INCLUDES AN ALT REQUIREMENT IN THE DESCRIPTION. AND THOSE ALTS ARE VERY NOTICEABLE ON THE DEPICTION (NOTE: USUALLY WHEN A SID IS CONCERNED WITH MINIMUM CLB GRADIENTS, THE REQUIREMENTS WOULD BE TO BE AT OR ABOVE A CERTAIN ALT BY A CERTAIN POINT). FINALLY, IT IS INDEED ESSENTIAL FOR PLTS TO BE EVEN MORE VIGILANT THAN EVER IN THIS ENDLESS VARIATION OF ENVIRONMENTS AND SEARCH FOR THE UNEXPECTED WITHIN THE STANDARD INSTRUMENT DEP.

Data retrieved from NASA's ASRS site as of July 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.