Air carrier medium large transport altitude deviation undershot altitude crossing restriction.

Attributes
ACN	172478
Time
Date	199103
Day	Fri
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : ric
State Reference	VA
Altitude	msl bound lower : 27000 msl bound upper : 29000
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport
Navigation In Use	Other Other
Flight Phase	cruise other descent other
Route In Use	enroute airway : j52
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : flight engineer pilot : atp
Experience	flight time last 90 days : 200 flight time total : 15700 flight time type : 4000
ASRS Report	172478
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : flight engineer pilot : atp pilot : cfi pilot : instrument
Experience	flight time last 90 days : 250 flight time total : 7000 flight time type : 2500
ASRS Report	172364
Events
Anomaly	altitude deviation : crossing restriction not met altitude deviation : undershoot non adherence : clearance
Independent Detector	other controllera other flight crewa
Resolutory Action	none taken : unable
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

We received clearance to cross 80 southwest of ric at FL280. Both first officer and I tried to enter the crossing fix into the FMC by typing ric/-80, but the FMC will not accept a new reference point when other points intercede. To clarify: J52 has a double bend between rdu and ric. Each bend is displayed on the FMC as a fix. The clearance to cross 80 southwest of ric establishes a new point between the 2 bends. In order to enter the crossing point, the fix must be designated with reference to either point a or point B. This requires reprocessing the information mentally, and increases the probability for error. In this case, I believe the error was compounded because the computer converted a 10 mi value to a .1 mi value. In any case, it seems like a good idea that whenever a crossing restriction will be routinely issued by ATC at a given point, that that arwy charts should show a named fix at that point. Failing that, then when given a crossing restriction referencing a DME form a VOR or intersection, clearance should be issued direct to that fix at that time, so that descent planning can being west/O confusion.

Original NASA ASRS Text

Title: ACR MLG ALT DEVIATION UNDERSHOT ALT CROSSING RESTRICTION.

Narrative: WE RECEIVED CLRNC TO CROSS 80 SW OF RIC AT FL280. BOTH F/O AND I TRIED TO ENTER THE XING FIX INTO THE FMC BY TYPING RIC/-80, BUT THE FMC WILL NOT ACCEPT A NEW REF POINT WHEN OTHER POINTS INTERCEDE. TO CLARIFY: J52 HAS A DOUBLE BEND BTWN RDU AND RIC. EACH BEND IS DISPLAYED ON THE FMC AS A FIX. THE CLRNC TO CROSS 80 SW OF RIC ESTABLISHES A NEW POINT BTWN THE 2 BENDS. IN ORDER TO ENTER THE XING POINT, THE FIX MUST BE DESIGNATED WITH REF TO EITHER POINT A OR POINT B. THIS REQUIRES REPROCESSING THE INFO MENTALLY, AND INCREASES THE PROBABILITY FOR ERROR. IN THIS CASE, I BELIEVE THE ERROR WAS COMPOUNDED BECAUSE THE COMPUTER CONVERTED A 10 MI VALUE TO A .1 MI VALUE. IN ANY CASE, IT SEEMS LIKE A GOOD IDEA THAT WHENEVER A XING RESTRICTION WILL BE ROUTINELY ISSUED BY ATC AT A GIVEN POINT, THAT THAT ARWY CHARTS SHOULD SHOW A NAMED FIX AT THAT POINT. FAILING THAT, THEN WHEN GIVEN A XING RESTRICTION REFERENCING A DME FORM A VOR OR INTXN, CLRNC SHOULD BE ISSUED DIRECT TO THAT FIX AT THAT TIME, SO THAT DSNT PLANNING CAN BEING W/O CONFUSION.

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.