IMHO bird radar is never going to get a tick in the box; reasons being.......
a. Aircraft to aircraft separation depends upon all participating (and squawking) acft inbound/outbound (or operating locally) being issued tracks, heights, speeds and hard altitudes to be at by specific distances, and on the odd occasion an orbit or diversion from track. Departing aircraft are scheduled to achieve orderly departure slot times - and all this directive info must be acknowledged and acted upon promptly by all parties in order to have orderly flow and an ongoing "avoidance contract". Anybody fails in his duty or misunderstands - and the fall-back is a TCAS RA. That more or less defines a minimum level of separation safety and achieves the regulatory standard. Above all, it's orderly and predictable. Inject a bird radar into that scene and you are calling for a Wild West scenario - if you expect the BIRDAR operator to be able to dictate an additional avoidance task or maintain a separation standard. The best he could ever hope to do would be to issue very short notice random warnings of imminent threat. Unilateral avoidance action by pilots would often breach their contract with ATC - and generate incidents of near collision or at least a loss of separation standards. The range from an airport to which he could do this is very debatable also.
b. Inject unpredictable flocks of birds into that ATC ballet and it's a whole new ballgame. What does it matter that birds may be flying in a particular direction at an unknown height at 50mph - if suddenly they can unpredictably wheel and turn or circle or be attacked by predators and break up as a flock? They can also be lost from radar due to aspect if they are proceeding individually. They can suddenly meld with permanent radar echoes or be lost due to proceeding tangentially to the radar head - and cancelled by MTI circuitry (moving target indicator). Once you inject the wild card of a wheeling flock (or two) into an orderly ATC situation you cannot start issuing urgent avoidances to aircraft for even minimal miss distances. That way lies bedlam in congested airspace. Compare it to a fleet of heavy bombers mixing it with swarms of predatory fighters. The bombers must maintain formation and tracking - because if they start weaving or mixing it with their aggressors, they will have mutual collisions - as well as collisions with the fighters (i.e. "the birds" in this simile).
c. Birds on, near or within 30 miles of an airport with dense traffic, constitute misguided missiles. Military radar operators can identify bogeys and their tracking towards an intended target, but anticipating bird-tracks is like trying to channelize quicksilver (i.e. mercury flows). Expecting ATC to inject birds into the avoidance contract would be like trying to choreograph a dogfight. The technology may exist but the operational practicality is practically unachievable. For "control", you first require "controllables".
d. The very practical solution is AVIANCOSH (attached email). It would be good out to any range from an airport and up to any hazard height. AVIANCOSH would clear birds from the flightpath without aircraft having to take anything much more than minimal avoidance action. The practical effect is both to detect hazards ahead on one's projected flightpath AND quickly taser the birds away from your own forward hemisphere (an automated process that could be tied into the autopilot and/or flight director) - i.e. once zapped the birds always peel off and dive at speed. It's their instinctive response to attackers. AVIANCOSH would not be weather limited and it would also work against all formsof ground-bound wild-life on the runways for take-off and landing..
e. AVIANCOSH would be an organic detector and deterrent and it featherbeds the process from an ATC point of view. In fact ATC doesn't need to know that you had to dodge a flock while thermic lance zapping the closer interlopers on your way through. The beauty of it all is that it's also an on-ground and airborne icing solution. If you doubt that the technology is there, look at the recent developments in the field and the incredible precision achievable with CNC milling and laser surgery techniques. Will the Birdar protect an unmanoeuvrable aircraft on its take-off roll? No it won't. Could Aviancosh? Yes. The same philosophy applies for the approach and finals, particularly below 1000 feet.
The only question is who will ultimately put the system together, test, qualify and commission it. 1998's Iridian/Roadshow is now making its way into the airline aviation world. I believe AVIANCOSH will also..... given time. We've seen that flocks of geese can bring down large airliners as well as bizjets. Geese can make it through the windshields of an A380 also. Perhaps in time an accident will dictate that such a system is far too expensive NOT to have. After all, that was eventually the story with take-off warning systems, radar altimeters, weather radar, windshear alerting, TCAS and EGPWS, was it not?
Monday, May 7, 2007
The FAA On Ice
Agency Solutions For Shedding Those Excess Pounds
The Federal Aviation Administration (FAA) is proposing to amend the airworthiness standards for transport category airplanes certificated for flight in icing conditions. The initiative is intended to improve safety for new designs for operation in icing conditions. The FAA would like to be able to specify an automated IPS (Ice Protection System) that not only warns but acts. The Agency says such systems would remove any question of when pilots are required to activate such measures. By being automated, proactive and pre- emptive, needless accidents could be avoided. It is a laudable exercise that up until now has been stymied by technical limitations and deficient design.
Comments are due 25 July. The proposed rule (at tinyurl.com/2pt4gx) is based on Aviation Rulemaking Advisory Committee (ARAC) recommendations to the FAA from the ARAC Ice Protection Harmonization Working Group or IPHWG). ARAC was asked to advise on ice detectors or other acceptable means to warn flightcrews of ice accretion on critical surfaces requiring crew action. Under existing regulations, the certification rules applicable to transport category airplanes for flight in icing conditions require that: "the airplane must be able to operate safely in the continuous maximum and intermittent maximum icing conditions of appendix C. Specifically addressed are operations in icing conditions that might adversely affect safety and installation of certain types of ice protection equipment and wing illumination equipment. Surprisingly, neither the operating regulations nor the certification regulations require a means to warn flightcrews of ice accretion on critical surfaces.
The benchmark accidents that are often cited as classic examples of icing perils are once again:
What the FAA does not address in this NPRM are the aspects covered by the ARAC which are most problematic:
According to the NPRM, these issues may be the subject of further rulemaking. The subject of supercooled large droplets (SLD), aka rain-ice or freezing rain, is the most vexing. Rather than broad-brush the whole subject, the NPRM concentrates upon the IPHWG's reviewed icing events and the accidents and incidents where the flightcrew was either completely unaware of ice accretion on the airframe, or was aware of ice accretion, but judged that it was not significant enough to warrant operation of the airframe ice protection system (IPS). The IPHWG concluded (and recommended to the FAA) that flightcrews must be provided with a clear means to know when to activate the IPS.
The FAA has, for certain airplane types, issued directives as to exactly when pilots should activate anti- and de-ice systems - in particular, deicing boots. The FAA concedes that darkness, high workload and the transparency of clear ice may make it difficult for pilots to determine the need. It also recognizes that the difficulties of observing ice accretions are applicable to any IPS that relies on the flightcrew's observations for activating the system, not just pneumatic deicing boots. The IPHWG concluded that installing a device to alert the flightcrew to activate the IPS would be an improved means to address these situations for future airplanes. A primary ice detection system would be one acceptable means. An advisory ice detection system, in conjunction with substantiated visual cues, would also be an acceptable means.
The complexity arises when the IPHWG stipulates that the acceptability would be contingent upon:
The NPRM concedes that an advisory icing detector isn't reliable enough to be a primary system - but it is seen as a strong supplement to the "proven unreliable" visual detection probabilities. The type of detector being discussed can be seen at newavionics.com. The cost of such an ice detector system would be around $6,000 per ice detector for a production airplane.
Another acceptable alternative to requiring an ice detector would be to require operating the IPS whenever the airplane is operating in conditions conducive to airframe icing. In this case, the flightcrew would activate the IPS in response to a specific air temperature threshold and the presence of visible moisture. Whichever method is employed, the FAA is now adamant that the proposed US dollars 25.1419(e) will require one of the three acceptable methods recommended by the ARAC Ice Protection Harmonization Working Group: a primary ice detector, visual cues and an advisory ice detector, or operation based on a trigger temperature plus visible moisture.
The FAA is concerned with the flightcrew workload created if an IPS must be manually cycled. Manual operation of the IPS could be a distraction during the approach and landing phases of flight which typically involve higher pilot workloads. The emphasis is therefore on having an IPS that is automatically cycled or operates on a continuous basis (for example, an anti-icing system). The proposed rule looks to eliminate workload concerns by stipulating either an IPS that works continuously or in a cyclic manner or an advisory system that would alert the pilots to activate the IPS. The rule would be applicable to all newly certificated part 25 airplanes.
At this point it's worth reviewing what Air Safety Week has said in the past about exploitation of new technology to drag deicing, anti-icing and preflight ground de-icing into the 21st century. Deicing boots and piped hot bleed air may have served their purpose but other solutions should be sought. ASW has previously "shed some light" on this:
Thermal laser wiping: The theory is that a twin laser unit sits atop the cockpit of a high-wing turboprop (and another under the nose of a low-wing turboprop) in an ice-guarded rear-facing cupola. It is memory-mapped with the airplane's anatomic profile.
The low-power laser continuously measures (via a mensuration mapping software program) the aircraft's profile, until it detects an anomaly associated with ice accretion. With the high-power laser armed by the ice-detector, it then commences thermal lasering of the aircraft's leading edges, engine intakes, propellers, pitots and forward wing sections. The cupola mounted above the flight deck would also handle the empennage. Such a system might weigh less than the unaerodynamic boots. Electric power demand might not be that great, as heavy-duty capacitors could be charged up over a period of time and then discharged for the periodic phased attacks on ice accretions. As per the standard inflation cycle for de-icer boots, the lasers could alternate phase (top cupola/bottom cupola) and run a 30 seconds on/30 seconds off cycle.
Perhaps this system could be called the Laissez-faire, a play on the word laser which might appeal to the French manufacturer of the ATR-72 (Laissez-faire = Non-interference in the affairs of others, as in 'ice go away'). (Air Safety Week 10 Nov 03 & 21 Nov 05)
In a further development of this concept, it was also postulated that, in conjunction with a close-in detection mode of airborne weather radar (or a detection mode of the mapping laser), the (now) forward facing cupola could be used as a laser weapon against birds in the flight-path with collision potential. Once "zapped" by the laser sufficiently far ahead, they'd peel off and dive clear (the usual behavior observed with birds just pre-strike)... or so the theory goes.
The FAA's NPRM seems to be a reasonable attempt to "break the ice" on a subject that's far more complex than this NPRM's coverage. However if the only outcome was to be that icing detectors would become mandatory in new designs, then that would eliminate a large pie-slice of the existing icing accident potential. The new focus should now be on coping with SLD and investigating new anti-icing technologies. The ultimate solution to the icing curse has been an ongoing enigma for aviation. The company that comes up with a workable futuristic system will be both feted and bonanza'd.
ASW Monday, May 7, 2007