Re: 747-400 Initial Cruise

Date:         22 Nov 97 20:41:23 
From:         Cass Alexander <>
Organization: ATC Systems Consultant
References:   1 2 3 4
Followups:    1 2 3
Next article
View raw article
  or MIME structure

Jan-Olov Newborg wrote:
> If modern nav-ATC equippment for freer flight (lateral airways) like the
> Swedish proposed ADS-B system, the problem not letting aircraft up high
> enough initially would be solved.
> US Airforce use the GNSS-transponder today for C5b Galaxy formation
> flying and Navy F18 Hornet is testing it.
> Jan-Olov Newborg
> Stockholm

Greetings Jan-Olov,

Several years ago, a Qantas 747 skipper mentioned to me that costs
associated with flying the big Boeings at non-optimum levels averaged
out at some 2000 Australian dollars (~ $1300 US) per hour per thousand
feet off the optimum level.

Qantas 747's and future 777 acquisitions will all include FANS 1
avionics to facilitate ADS transponding and controller-pilot data link
coms. Given that Australian ATC centers control 11% of the worlds
airspace, and that most of that airspace lacks radar coverage, the
ability of aircraft to update their positions to the responsible ATC
system, either on a periodic basis or in response to a controller issued
"one-shot" request goes some way to providing ATCs with a mechanism for
minimising approved separation techniques, and thereby optimising the
use of the most popular flight corridors.

Testing of ADS in the new Australian Advanced Air Traffic System
(TAAATS) has revealed the extraordinary accuracy of this emerging
technology, with ADS and radar tracks on the same aircraft being
coincident to fractions of a kilometer.

You are therefore partially right in saying that:

"If modern nav-ATC equippment for freer flight (lateral airways) like the
Swedish proposed ADS-B system, the problem not letting aircraft up high
enough initially would be solved."

However, it must be borne in mind that several other factors play a
vital role in the successful use of technology such as ADS and CPDLC in
the management of complex and extensive air space, specifically:

1. The ability of the responsible traffic management authority to accept
the air-derived data from participating aircraft and display it to their
controllers. In the absence of ground-based FANS facilities, separation
reductions to minimas will not materialise.

2. The administering authority must also have created and promulgated
safe separation standards which can be used by the controllers under a
variety of both operational circumstances and system mode degradations

3. Optimally, each aircraft which wishes to operate in airspace which
utilises avionics-derived position data relayed to the ATC system should
be fitted with the appropriate on-board equipment. Especially where
large numbers of crossing tracks are combined with large numbers of
aircraft using those tracks in a procedural control (no-radar)
environment, a single non-ADS equipped can impact on the separation
standards to be applied to many other aircraft, as its lack of
appropriate avionics require controllers to employ restrictive
procedural separation standards rather than the emerging ADS standards,
which are much less "draconian".

As more aircraft are fitted with FANS avionics, and the number of city
pairs (and therefore crossing air-routes) being flown by airlines
continues to burgeon, I can foresee the day when ATS management
authorities world wide will preclude non-FANS aircraft from operating in
high traffic density, multi-route non radar controlled airspace in which
FANS-based traffic separation facilities are available from the ATS
service provider.

Fanciful ?

A precedent already exists in many countries, whereby aircraft which are
not fitted with SSR radar transponders are prohibited from entering
controlled airspace in which radar is the primary ATC separation tool.

In the words of the CEO of Airservices Australia (Bill Pollard),
"(TAAATS is) the world's first fully-integrated air traffic management
system" and its majority of its cost of AUD350 million will ultimately
be recovered from airlines; 95% of Airservices Australia's revenue is
derived from RPT operations.

Those paying for such an costly (though not necessarily expensive)
system will no doubt equip their fleets at the earliest opportunity,
then support moves to decline access to the airspace within which they
operate to non-airline, non-ADS equipped aircraft.

>From their perspective, if the user pays, the user benefits.

Hoperfully, aircraft FANS package costs will plummet, as did the costs
of radar transponders between their inception and the present.

With a vast area comprising both continental and oceanic airspace to
administer, Airservice Australia can only fully offer FANS-derived
benefits to operators when participation is universal. The same is true
of other ATS service providers throughout the world.

The bottom line is that whenever airlines complain about restrictive ATC
practices in airspace within which advanced technologies such as FANS
are in operational use, perhaps they should first have checked whether
they are contributing to those restrictions by - in addition to parallel
scheduling - failing to equip their fleets with avionics which take full
advantage of those advanced services.

Cass Alexander
(The views expressed herein are my own; they are not necessarily)
(those of any organisation for which I may presently be working.)