GPS
Although it seems very unlikely that the crew would have been relying on GPS at the time of the WP change it is interesting that the comments on the accuracy (or possibly lack of accuracy) of the GPS are a bold warning in the CA Interim Release Annex O where 2.2 says:
TNL 8000 GPS GPS has not yet been declared operational(at IOC) by the US DoD and accuracy is therefore not guaranteed at any level. Even when GPS is declared operational by the US, accuracy of the TNL 8000 SPS GPS could degrade substantially without any indications to the crew. For this reason SPS GPS should not be used as the sole navigation aid.
The crew would have known this and presumably would not have been relying on GPS - but is is another indication of the fitness for purpose and the overall airworthiness of the Chinook Mk 2 at that time.
JB