A Sonk post, I liked it to I am moving it here, with all due respect to Sonk.
By: sonk1
13 Aug 2005, 11:06 AM EDT
Msg. 7133 of 7133
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Wingman: Is HUD/EVS About to Become Mainstream?
According to a recent report in Flight International, JetBlue Airways wants the 100 new Embraer 190s it has on order to be equipped with Rockwell Collins Flight Dynamics’ new‑generation liquid-crystal HUD, with the possibility of adding EVS in due course. Does this indicate the coming of age for these nascent technologies? Wingman believes yes, and here’s why:
First, all of the major air transport airframe manufacturers, Airbus, Bombardier, Boeing, and Embraer are now offering head-up displays and some form of enhanced vision as optional equipment on a few of their models. And high-end business jet manufacturers such as Gulfstream Aerospace, Boeing (Business Jet), Bombardier, Embraer and Dassault Falcon, make HUDs an option on some of their aircraft types. Beyond that, Gulfstream has certified EVS on several of its types, and says it has become a popular choice. Bombardier and Boeing will soon be offering an EVS as well.
Second, three of the largest avionics suppliers, Honeywell, Rockwell Collins and Thales, include HUDs in their product portfolios, and Honeywell and Thales have already announced EVS partners: Honeywell with Kollsman and Thales with CMC Electronics. Rockwell Collins’ Flight Dynamics is working with Boeing on an EVS for the BBJ.
Third, a number of airlines have already invested in HUDs – albeit with spotty consistency – often to address a specific need or individual aircraft-type low-visibility weakness. American, ATA, Delta, Southwest, and UPS have followed HUD-pioneer Alaska Airlines and its regional partner Horizon, along with a significant number of other airlines – mainly in Europe.
And then in the boldest move yet, FedEx let it be known earlier this year that it would equip its A300s, A310s, MD-10s and MD-11s with Honeywell’s HUD/EVS.
Enhanced Vision Rule Validates Its Low-Visibility Utility
Some of the new interest in both HUDs and EVS undoubtedly comes because of the FAA’s new rule authorizing the use of, what it describes as, an enhanced flight vision system (EFVS) to accomplish low-visibility operations not previously possible.
Specifically, the new rule allows a pilot to use EFVS to identify specific visual cues at either a CAT I decision height (DH) or minimum descent altitude (MDA) by using enhanced vision, and then continue the approach to an altitude of 100 feet, after which “natural vision†is required to complete the landing.
This, by itself, might not appear to be a great operational enhancement, since for most operators; the occasions when this capability can be exploited will be operationally rare. But Wingman believes that besides validating the utility of this technology, for a new never-before-allowed operational procedure, the rule hints at how EFVS might be applied to even greater use in the future.
Modern Civil HUD Attributes
Modern civil HUDs are far more than repeaters of traditional instruments displayed in front of the cockpit windshield. They are truly unique flight guidance systems, which incorporate several, highly intuitive what-to-do indicators not found even with modern “glass†primary flight displays. Their "commands" include a takeoff steering director; an approach flight director; a flight-path-angle reference cue when precision guidance is not provided; an energy management indicator that shows both the aircraft's speed error and precisely how to correct the variance; a flight-path vector that shows exactly where the aircraft is going; an angle-of-attack indicator – that automatically appears if needed; and a flare cue to help the pilot accurately complete the landing maneuver.
HUD/EVS Safety Case
Boeing's latest "Statistical Summary of Commercial Jet Airplane Accidents," notes that between 1959 and 2003, 51 percent of worldwide commercial jet fleet hull losses and fatal accidents occurred during final approach and landing (six percent and 45 percent respectively). Twelve percent occurred during takeoff and five percent during initial climb to flap retraction. This means that more than two-thirds of serious accidents happen in flight regimes where modern HUDs and EVS can have the most beneficial affect.
Some of these accidents have been associated with poor visibility, including just plain darkness. These include, for example: Two B-747s colliding on a runway at Tenerife; a B-757 hitting a mountain side during a nighttime descent into Cali, Columbia; a Gulfstream jet hitting the ground short of the runway during a night, non-precision approach into Aspen, Colorado, in marginal weather; a MD-87 colliding with a Cessna Citation on a foggy runway at Milan, Italy; a B-747 striking construction equipment while attempting to take off on a stormy night, on a wrong runway, at Taipei; and a B-737 landing on top of a commuter aircraft holding in position for takeoff on the runway at Los Angeles after dark.
All of these incidents or accidents might have been avoided if the pilots could have seen what was happening.
New Paradigm for Satnav Approaches?
Since the late 1990s the FAA has been working to implement its GPS Local Area Augmentation System without success. While much has been made of the agency’s difficulty to develop a viable business plan, there is an operating issue as well.
It appears that the main problem bedeviling the use of satellite navigation for lower minimums approaches is the difficulty of totally eliminating the possibility of misleading navigation information – commonly referred to as signal integrity – that has appropriately stringent requirements for “blind†operations nominally below CAT I minimums. But doesn’t the new FAA EFVS rule establish that EVS can remove the pilot’s "blindness"? After all, with EVS, the pilot will see if the system is "lying" and can take appropriate action.
Until the EFVS rule, very low-visibility approaches were predicated on CAT III-capable autoland or HUD systems, using an unimpeachable navigational signal. But now, even non-precision approaches can be flown in instrument conditions down to 100 feet – and perhaps lower in the future – if the pilot can see the necessary visual cues, without these daunting requirements.
EFVS won’t mean autolands will be junked of course, and LAAS will likely have other important future uses, at least at some airports. Nevertheless, a new EFVS-based requirement model might mean that the Wide Area Augmentation System and the European Geostationary Navigation Overlay Service (EGNOS) are sufficient for many operations, including those in very low visibility, for airplanes equipped with EVS technology.
Given this possible new paradigm for approach requirements, along with all of the other advantages of HUD/EVS, Wingman believes the increasing interest in this technology is warranted, and deserves even more attention.
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