In response to an NTSB recommendation, Honeywell is revising the software of its Mark XXII enhanced ground proximity warning system (EGPWS) for helicopters. The Safety Board last month warned that the failure of the radio altimeter could prevent the EGPWS look-ahead feature from functioning in flight, unbeknownst to the pilot. The NTSB on April 14 sent a recommendation to the FAA recommending that it require helicopter operators to install a software fix for the Mark XXII unit. Honeywell has issued a service information letter to deal with the issue while the software revision is developed.