A B757 departed segu and received an egpws warning because of a map shift and an ATC warning that th...

Attributes
ACN	918910
Time
Date	201011
Local Time Of Day	0001-0600
Place
Locale Reference	SEGU.Airport
State Reference	FO
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	B757-200
Operating Under FAR Part	Part 121
Flight Phase	Climb Initial Climb
Route In Use	Other Controlled
Flight Plan	IFR
Component
Aircraft Component	INS / IRS / IRU
Person 1
Function	Pilot Flying First Officer
Experience	Flight Crew Last 90 Days 150 Flight Crew Total 16000 Flight Crew Type 5000
Person 2
Function	Captain Pilot Not Flying
Qualification	Flight Crew Air Transport Pilot (ATP)
Experience	Flight Crew Last 90 Days 100 Flight Crew Total 11000 Flight Crew Type 3600
Events
Anomaly	Aircraft Equipment Problem Critical

Narrative:

Immediately after takeoff; we received a faulty egpws warnings due to a possible map shift; along with cautions; and audible horns. We confirm[ed] the faulty egpws warning by visual indications outside the aircraft window and our known position. While climbing to our first assigned fix in LNAV; ATC advised that we were not proceeding to our assigned position of present position direct to vulky. At this time we were able to confirm that we had and continued to have a map shift. We had no FMC or IRS messages to indicate a fault or error. We asked for radar vectors and used VOR's as our primary source of navigation for the remainder of the flight. Working with dispatch we diverted. Upon landing; the mechanic confirmed that our center and right IRS's were not accurate and the left IRS and FMC present position were accurate. Maintenance tested and reset the IRS's and the flight continued uneventfully. Logbook entries were entered as required. Note: we never had an indication of a map shift on the ground prior to takeoff. We confirmed and verified the runway and that the runway was within the triangle of our ehsi map prior to takeoff. ATC cleared our flight direct to vulky after takeoff on runway 03.

Original NASA ASRS Text

Title: A B757 departed SEGU and received an EGPWS warning because of a map shift and an ATC warning that they were not proceeding to the initial fix. The crew used VOR navigation and diverted to an enroute airport where maintenance confirmed that only one of three IRS's was accurate. The IRS's were reset and the flight continued normally.

Narrative: Immediately after takeoff; we received a faulty EGPWS warnings due to a possible map shift; along with cautions; and audible horns. We confirm[ed] the faulty EGPWS warning by visual indications outside the aircraft window and our known position. While climbing to our first assigned fix in LNAV; ATC advised that we were not proceeding to our assigned position of present position direct to VULKY. At this time we were able to confirm that we had and continued to have a map shift. We had no FMC or IRS messages to indicate a fault or error. We asked for Radar vectors and used VOR's as our primary source of navigation for the remainder of the flight. Working with Dispatch we diverted. Upon landing; the Mechanic confirmed that our center and right IRS's were not accurate and the left IRS and FMC present position were accurate. Maintenance tested and reset the IRS's and the flight continued uneventfully. Logbook entries were entered as required. Note: We never had an indication of a map shift on the ground prior to takeoff. We confirmed and verified the runway and that the runway was within the triangle of our EHSI map prior to takeoff. ATC cleared our flight direct to VULKY after takeoff on Runway 03.

Data retrieved from NASA's ASRS site as of April 2012 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.