B757 flight crew has a track heading deviation during mia departure from mia.

Attributes
ACN	700744
Time
Date	200606
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : mia.tracon
State Reference	FL
Altitude	msl bound lower : 5000 msl bound upper : 7000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : mia.tracon
Operator	common carrier : air carrier
Make Model Name	B757-200
Operating Under FAR Part	Part 121
Flight Phase	climbout : initial
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
ASRS Report	700744
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
ASRS Report	700076
Events
Anomaly	non adherence : clearance non adherence : published procedure other spatial deviation
Independent Detector	other controllera
Resolutory Action	controller : issued advisory flight crew : became reoriented flight crew : overcame equipment problem flight crew : returned to intended or assigned course
Consequence	faa : reviewed incident with flight crew
Supplementary
Problem Areas	Aircraft Flight Crew Human Performance
Primary Problem	Flight Crew Human Performance

Narrative:

Normal preflight on FMC and flight plan; all checked ok. During initial climb ATC requests intercept of valley transition (058 degree radial vkz). When I select legs page; the route is gone and I cannot reselect any points (points disappear when selected to route or legs page; execute light illuminates without showing point). During this time we put the raw data on the map display to show the green line or 058 degree radial of vkz. I told the captain there's the raw data; and went back heads down to fix the route. The captain started the turn early and end up paralleling the course to the west of the transition by about 3 mi. ATC queried us and after the confusion we asked for a vector and were handed off to ZMA. After we were on the vector I went back heads down and found out I could get navigation points into route #2. After verifying our position with the init page (GPS coordinates) and waypoint page; we were on our way. Later; I was able to move all information back into route #1 and all worked normally. We also noticed that the mia; bos and the company route #2 were all still there; the route was all that was missing. After the fact; I should've not stayed head down during a critical time of flight; as well as use the compass rose page on the HSI; rather than map with the raw data selected. The captain was in a greater range and this is why we thought the aircraft was approaching the radial; but it was actually a few mi ahead. However; I've never encountered an FMC anomaly like this before. I've seen the route drop out; but it was always ready to be reactivated. This route was gone! The only way I know to purge a route after it's been activated is to select the destination to the origination on the route page. Supplemental information from acn 700076: I was flying; but didn't realize that I had changed to expanded scale when looking for the magenta line; and failed to go back to the 10 mi scale or expanded mode when intercepted the VOR. This caused me to turn west of course before correcting for this. ATC asked if we were intercepting the radial; and at that time; I realized I was west of course and corrected.

Original NASA ASRS Text

Title: B757 FLT CREW HAS A TRACK HDG DEV DURING MIA DEP FROM MIA.

Narrative: NORMAL PREFLT ON FMC AND FLT PLAN; ALL CHKED OK. DURING INITIAL CLB ATC REQUESTS INTERCEPT OF VALLEY TRANSITION (058 DEG RADIAL VKZ). WHEN I SELECT LEGS PAGE; THE RTE IS GONE AND I CANNOT RESELECT ANY POINTS (POINTS DISAPPEAR WHEN SELECTED TO RTE OR LEGS PAGE; EXECUTE LIGHT ILLUMINATES WITHOUT SHOWING POINT). DURING THIS TIME WE PUT THE RAW DATA ON THE MAP DISPLAY TO SHOW THE GREEN LINE OR 058 DEG RADIAL OF VKZ. I TOLD THE CAPT THERE'S THE RAW DATA; AND WENT BACK HEADS DOWN TO FIX THE RTE. THE CAPT STARTED THE TURN EARLY AND END UP PARALLELING THE COURSE TO THE W OF THE TRANSITION BY ABOUT 3 MI. ATC QUERIED US AND AFTER THE CONFUSION WE ASKED FOR A VECTOR AND WERE HANDED OFF TO ZMA. AFTER WE WERE ON THE VECTOR I WENT BACK HEADS DOWN AND FOUND OUT I COULD GET NAV POINTS INTO RTE #2. AFTER VERIFYING OUR POS WITH THE INIT PAGE (GPS COORDINATES) AND WAYPOINT PAGE; WE WERE ON OUR WAY. LATER; I WAS ABLE TO MOVE ALL INFO BACK INTO RTE #1 AND ALL WORKED NORMALLY. WE ALSO NOTICED THAT THE MIA; BOS AND THE COMPANY RTE #2 WERE ALL STILL THERE; THE RTE WAS ALL THAT WAS MISSING. AFTER THE FACT; I SHOULD'VE NOT STAYED HEAD DOWN DURING A CRITICAL TIME OF FLT; AS WELL AS USE THE COMPASS ROSE PAGE ON THE HSI; RATHER THAN MAP WITH THE RAW DATA SELECTED. THE CAPT WAS IN A GREATER RANGE AND THIS IS WHY WE THOUGHT THE ACFT WAS APCHING THE RADIAL; BUT IT WAS ACTUALLY A FEW MI AHEAD. HOWEVER; I'VE NEVER ENCOUNTERED AN FMC ANOMALY LIKE THIS BEFORE. I'VE SEEN THE RTE DROP OUT; BUT IT WAS ALWAYS READY TO BE REACTIVATED. THIS RTE WAS GONE! THE ONLY WAY I KNOW TO PURGE A RTE AFTER IT'S BEEN ACTIVATED IS TO SELECT THE DEST TO THE ORIGINATION ON THE RTE PAGE. SUPPLEMENTAL INFO FROM ACN 700076: I WAS FLYING; BUT DIDN'T REALIZE THAT I HAD CHANGED TO EXPANDED SCALE WHEN LOOKING FOR THE MAGENTA LINE; AND FAILED TO GO BACK TO THE 10 MI SCALE OR EXPANDED MODE WHEN INTERCEPTED THE VOR. THIS CAUSED ME TO TURN W OF COURSE BEFORE CORRECTING FOR THIS. ATC ASKED IF WE WERE INTERCEPTING THE RADIAL; AND AT THAT TIME; I REALIZED I WAS W OF COURSE AND CORRECTED.

Data retrieved from NASA's ASRS site as of January 2009 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.