Blue Avionics Solves TAWS Mode 5 Alerting Conundrum
Blue Avionics makes configurable adaptable avionics equipment that solves interface issues on a variety of aircraft.

As NextGen capabilities are added to avionics that weren’t designed with modern conveniences such as LPV approaches, making all these technologies work together smoothly is an issue. Blue Avionics has studied these issues and developed configurable adaptable avionics equipment that interfaces between various types of equipment. The company’s BA-440 Router/Filter, for example, allows operators to take advantage of advanced technology and eliminates the need to replace older avionics with far more expensive new products.

Airline airBaltic wanted to upgrade its Bombardier Q400s with Universal Avionics UNS-1Ew satellite-based augmentation system (SBAS) FMSs. This would give the fleet the ability to fly LPV approaches, which are rapidly supplementing ILS approaches and replacing non-precision approaches in the U.S. and Europe. However, the FAA and EASA require that TAWS Mode 5 alerting be available from the aircraft’s enhanced ground proximity warning system (EGPWS) when flying ILS and LPV approaches, and there was no way to provide the alerting without buying a new EGPWS or FMS with that capability builtin. 

TAWS Mode 5 alerting gives pilots aural glideslope warnings if the aircraft is flown too far below the glideslope during an ILS or LPV approach. The Honeywell EGPWS installed in the airBaltic Q400s does not have the Mode 5 alerting for LPV approaches, while it does provide the alerting for ILS approaches. 

The Blue Avionics BA-440 solves this problem by detecting when the aircraft is flying an LPV approach and switching the output from ILS to pseudo ILS and thus instructing the EGPWS to deliver TAWS Mode 5 alerting. The BA-440 also helps facilitate alerting for RNP GPS approaches. “It will work with any EGPWS or TAWS that has ILS Mode 5 alerting,” said Ross Cairns, Blue Avionics' founder and managing director. 

The BA-540 offers additional adaptable avionics features, and for business aircraft, is being used to interface Rockwell Collins Pro Line 21 displays with the head-up display. Another application—in a Boeing 747—is using the BA-540 as an overspeed computer and data concentrator for air data.