By S.L. Fuller | November 3, 2017
The FAA’s final rule for the use of enhanced flight vision systems (EFVS) were meant to streamline certification — something the agency is trying to do in general. But the final rule does not signify an end to the discussion. In fact, a set of amendments are set to start rolling out in the near future. Randall Bailey of NASA Langley Research Center said, however, there is a logical final step in EFVS applications.
Bailey will be discussing the topic at our Avionics for NextGen conference Nov. 15 to 16 at the Hilton Washington Dulles Airport in Herndon, Virginia. Ahead of his presentation, here’s what you should know about the EFVS rule and applications.
The changes are aimed at streamlining and clarifying the certification and operation of EFVS, with attention to all operators, but in particular, to Part 121 and 135 operators.
While these changes are important, the most significant impact may be that the rules set a precedence where for the first time, an electronic means of vision may be used in lieu of natural vision for approach, landing and roll-out. This precedence may open the path for new and unique technologies and operations.
The changes will not disrupt operations, but there may be changes. The impact should be easily managed, but with any change, there is always uncertainty related to those that don’t fully understand the technology, its impact.
The irony is that EFVS actually is intended to minimize disruptions. A goal of EFVS operations is to be independent of the actual outside weather and visibility, very much unlike today. Today, as the weather degrades, we have significant air traffic disruption. Weather creates a dichotomy of operations — visual flight rules (VFR) and instrument flight rules (IFR). Because the flight crew cannot see due to weather obscuration or visibility restrictions, we change air traffic procedures, separation procedures, roles and responsibilities. These different operating rules cause disruption. Delays due to weather cause disruption.
EFVS may not be able to completely mitigate disruption in weather (i.e., significant weather such as icing, heavy rain, etc. affects aerodynamic performance and EFVS won’t stop that), but EFVS might one day enable visual-like flight operations to be continually maintained. EFVS might enable one set of flight rules that are unchanging, consistent. The weather would not disrupt air traffic flow and operations. The same procedures are used in all-weather. By this, EFVS might significantly reduce weather-induced disruptions — traffic delays — and increase operational efficiency.
There is some significant work yet to be done.
True all-weather performance of EFVS must be achieved with levels of availability, reliability and performance expected by Part 121 operators. New sensor and computing technologies are emerging to meet these goals, but they have not yet been operationally proven.
Operational credit for EFVS equipage needs to extend to takeoff. Requirements are needed for this, and they should be available shortly (i.e., the use of EFVS to enable lower minima takeoff).
The next hurdle would be the use of EFVS (and related technologies) for low-visibility surface operations. Today’s auto-land systems can fly to extremely low visibility minima, just like future EFVS, but once off the runway, the pace of surface operations is extremely slow because a pilot’s natural vision is the only sensor today that provides awareness for surface operations. Enhancing flight crew visibility by EFVS during surface operations offers the potential for significant improvements in surface operations tempos and possibly, reductions in airport infrastructure for low visibility surface operations.
Ultimately, the goal of EFVS technologies is to enable the concept of equivalent visual operations. We are not trying to eliminate what is good about IFR operations (i.e., strategic planning, balanced workload for air traffic controllers and pilot workload, flight path predictability and stabilized approach procedures), but we do want to capitalize on the communications, navigation and surveillance upgrades that NextGen has fostered and couple them with the integrating tool of EFVS.
An example is required navigation performance (RNP) arrivals. Many are in place to create operational efficiency (shorter flight times) or reduced environmental impact. But the weather minima for these arrivals are much higher than instrument landing system approaches. When the weather degrades, these approach procedures are stopped. These procedures would not have to stop if the EFVS is capable of imaging the required visual references before the RNP decision altitude even as the weather minima decrease. This is just one of the examples that the integration of disparate NextGen technologies can bring, if properly molded, demonstrated, and implemented.
And as you continue along this paradigm, the elimination of the VFR/IFR dichotomy, as discussed above, is the logical final step in EFVS applications.