Harry Hopkins/DUBLIN
AIRLINE PILOTS have issued strong warnings about the premature use of new technology in air-traffic operations, but the absence of technology troubles them as well, it emerged at the annual conference of the International Federation of Air Line Pilots Associations (IFALPA) in Dublin, Ireland, on 20-23 March. It also became apparent that a dearth of technology in parts of the developing world is still a prime concern for pilots.
Satellite navigation is available worldwide and datalinking is around the corner, observes IFALPA, but inadequate voice communications and sub-standard air-traffic control (ATC) in large parts of the world remain a problem.
IFALPA has decided to shift its focus to raising the aviation safety performance of Third World countries and to the air-transport infrastructure they can offer. The conference noted that, while the 20 largest airlines own half the world's fleet, they have less than one-fifth of the world's hull-loss accidents. The Federation, it seems, is starting its crusade by streamlining its own communications, including expanding its electronic-mail links and using "position papers" to outline its developing policy between conferences.
At the top of IFALPA's list of "premature-technology" concerns is the use of airborne collision-avoidance systems (ACAS) for monitoring in-trail separation on climb or descent. Federation president Capt Rob McInnis singles out the activities of the Informal South Pacific Air traffic services Co-ordinating Group (ISPACG), highlighting the fact that, in part of the Pacific, lateral separation has already been reduced to 110km (60nm), with plans to reduce lateral and longitudinal separation to 90km, and then 55km. "Earlier fears that the [US Federal Aviation Administration], Australian and New Zealand elements of ISPACG would continue their headlong rush were not unfounded," he says.
"IFALPA, assisted by the International Federation of Air Traffic Controller Associations, has played a major role in attempts to prevent this", McInnis says, emphasising, however, that "...we are no less eager than the airlines to see reduced separation and an increase in the traffic flow on a global scale. The overriding need is to have the enhancements in communications, navigation facilities and surveillance all in place and proven, before separation minima can be effectively reduced."
The Federation strongly backs the more measured approach of the International Civil Aviation Organisation (ICAO) in pursuit of a uniformly safe operating environment. Airline operators are particularly interested in having a 'level playing field' for their commercial operations but, points out Capt Ted Murphy, IFALPA Principal Officer for technical matters, "...some states are attempting to bypass the formal ICAO process by use of informal and limited regional groupings. Many states and airlines are changing their work practices to avoid the full rigour of dispassionate and open investigation of their technical proposals".
Murphy observes: "Changes to long-accepted standards are being introduced in selected areas of the globe - and then being exported [based on] their supposed regional acceptability... Most of us would be well advised to enquire of our own administrations what they are doing to ensure the effectiveness of ICAO, and to protect its future."
A consistent theme was the aim of achieving global safety effectiveness through ICAO, with full backing and finance by the international community - and a balanced introduction of advanced technology. "It's ludicrous," says Murphy, "that we are having these discussions on high technology, yet [ATC] communication on HF [high-frequency wavebands] continues to be thought acceptable."
McInnis explains: "The aspirations of certain groups to use ACAS for purposes other than those for which it was originally designed and licensed grows. IFALPA does not oppose the principle of in-trail climb or descent, just the method presently proposed. If the equipment is improved, to satisfy us of its calibre and reliability, we are prepared to consider such procedures."
In particular, IFALPA called for reliable ACAS operation to be proven at ranges of up to 200km or so, used with suitably large displays. The Federation endorses the use of the in-cockpit traffic-alert and collision-avoidance system (TCAS) in its full operational mode at all times on aircraft now equipped - but only in the short-range tactical role for which the system was designed.
TCAS AND ITS PROBLEMS
There are some misgivings about TCAS, however. "We are not convinced on positive identification," Murphy says. "Some TCAS displays do not continually show proximate traffic, for example. We note in particular that the trials supported by the FAA have taken place only outside US national airspace."
Murphy adds: " There are no industry standards for training in ACAS either. In the long term, identification should be through Mode S [data] linking between aircraft."
AlliedSignal Aerospace, which has installed about 4,000 TCAS sets, answered some of these points, giving a presentation on the latest modification to TCAS II. The amendment is the introduction of US Change 7.0 software developed by the Radio Technical Commission on Aeronautics (RTCA).
Change 7.0 software is expected to be the subject of an FAA notice of provisional rule-making towards the end of the year, leading to an airworthiness requirement for its implementation, planned for the year 2000 in parallel with Europe and ICAO. Some Far Eastern states are believed to be prepared already to follow this time schedule.
The previous Change 6.04A software has reduced the number of nuisance resolution advisories (RAs), according to AlliedSignal. These were caused by high vertical climb rates at low level and have been dealt with by extending the trigger times. Nuisances still persist at higher altitudes, however, where the RA trigger is less delayed.
Change 7.0 software is intended to be more robust in multi-aircraft situations and to have a logic consistent with ICAO standards and recommended practices for ACAS. Changes are to be made to the miss-distance filter (which may also avoid nuisance-warnings from rapidly climbing threats) and to some features of the display and voice warnings.
Operational procedures used by pilots need to be studied further, says AlliedSignal. Analysis of the record of warnings and pilot responses, using the compulsory 6.04A software, has been difficult to interpret. Often no action in response to a real threat has been taken where visual contact has been established. This is renewing the debate on compulsory compliance with RAs, especially in the RTCA Operations Working Group.
MODE S PLANS
A requirement for basic Mode S, with fixed datalink message length, may be defined in Europe by mid-1996, IFALPA notes. Extended-message capability is not due until early 1999. AlliedSignal Aerospace says that it intends to release a Mode S transponder with this capability as the Change 7.0 software comes into effect.
Meanwhile, an evaluation of the down-linking to ATC of any TCAS RA message to the pilot is planned to be carried out at Boston, Massachusetts, and oceanic in-trail manoeuvres will continue to be developed.
"We can no longer divide many of today's aviation technical issues into discrete disciplines," McInnis says. "Problems are arising in flightdeck automation and in the implementation of the global navigation-satellite-system [GNSS] concept."
BASIC PROBLEMS
Problems can arise, however, where advanced equipment is used in a basic environment, McInnis says. The conduct of non-precision approach procedures using flight- management systems (FMS) has, for example, attracted long discussion in committee.
Since the FMS is not approved as an approach aid, it cannot be relied on absolutely. IFALPA draft policy only recommends its use subject to careful verification of position, but its use is believed to lower workload and can stabilise approach navigation on autopilot control. Many pilots believe that global-positioning-system (GPS)-based navigation for the approach phase may require "non-precision" to be redefined. Above all, however, pilots rate a steady final approach as being safe.
IFALPA, which has long identified and categorised deficient areas of the world, now supports a more steady and equitable introduction of modern technology on a global basis. It seems that pilot associations which are affiliated to IFALPA feel that, in some respects, modern technology is now being introduced in an almost arrogant manner.
Source: Flight International
