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Published: 4 March 2019
Effective: 4 March 2019

ATA Chapter: 34

Subject:

This Continuing Airworthiness Notice (CAN) is issued to alert affected operators that the GPS week number will roll over from 1023 to zero on the 6th of April. The last week zero was in August 1999.

Applicability:

All operators with aircraft fitted with a GPS receiver

Applicability:

All operators with aircraft fitted with a GPS receiver.

Purpose:

This Continuing Airworthiness Notice (CAN) is issued to alert affected operators that the GPS week number will roll over from 1023 to zero on the 6 th of April. The last week zero was in August 1999.

Background:

The GPS uses a 10-bit field to encode the week number in each time message, which has a maximum value of 1024. Once this limit is reached the GPS receiver resets the week number to zero and starts recounting.

Recommendation:

Many GPS receiver manufacturers have prepared for the rollover event and their receivers will operate without any issues. However, older receivers may not reset the week number to zero as expected. Operators with older GPS receivers should contact their avionics maintenance provider for guidance.