Air to Air Refuelling in Civil Aviation, An Opportunity & A Vision Dr ...

Fig. 32 shows possible options. Reverse tanking
(tanker behind the receiver) with boom and
receptacle may well be the preferred option. The
tanker aircraft will do all the positioning and control
work whilst the receiver aircraft continues on its
way. There have been many recent advances in
AAR systems e.g. in differential GPS and
autonomous refuelling, RARO, night vision etc. as
mentioned in previous papers
Fig. 33 shows various tanker capabilities (fuel
off-load and radius) currently envisaged by the
military. The civil interest will be over a range of
about 1000nm (radius 500nm).
4.6. Phasing in AAR
This is related to the time and finances available.
A worldwide network of bases for tanker operations
can be envisaged. This would serve airlines using
3000 nm range aircraft equipped with AAR
receptors. At present, operators tend to fall into
various categories: Cargo, Passenger, Passenger and
Cargo, Domestic (short haul), International (short
and long haul), National (“Flag carriers”) and
privately financed. Some diversity will exist with
the introduction of civil AAR. A small carrier,
equipped with short to medium range aircraft, could
buy-in AAR services and offer long-haul flights.
The AAR services may operate along the same
economic principles as airport and ATC services.
Based on figures already introduced, each
tanker, in a day, can undertake 8 to 12 flights and
service 20 to 30 aircraft. ICAO world airline data
indicated 1,672,000,000 passenger movements
worldwide in 2000, together with 33,500,000 tonnes
of cargo. We assume that 25% of the passenger and
50% of the cargo departures were long haul (6000
nm). Using our 3000 nm aircraft with AAR for
these long haul operations we would need 3,260
AAR operations daily. This equates to a global fleet
of about 160 tankers. Such estimates can be further
refined in due course.
The civil AAR operations will be phased in over
a period of time. It would be prudent to commence
with cargo aircraft to build up public confidence for
accepting the new procedures. During this
introductory phase, AAR service suppliers would
begin to generate finances, thereby encouraging
financial interest.
It is possible that a cargo carrier would seize the
opportunity of providing the tanker services,
especially if they already had operational /
maintenance bases, strategically placed along the
long-haul routes.
The United States Transportation Command
(USTRANSCOM) coordinates the movement of
materials and supplies worldwide for the US
military. Aircraft used for these operations include
the C-5 and the C-17. Frequent use is made of AAR
for the longer ranges. A proof of concept and initial
evaluation of AAR in civil aviation to reduce fuel
consumption could be undertaken by the military.
Market Forecasts
Using the latest Boeing Studies (Ref.15), one
can conjecture with AAR, a change in the new
deliveries at least, See Table 1. There is always
6
need for more detailed work including fuel savings
and costs!
In the above forecasts for 2027, 3,890
Freighters are included. These comprise 35%
standard body (80 tonnes).
With AAR, the Twin-Aisle aircraft needed will
be the smaller range versions, either modified or
new (more fuel efficient with increased payloads,
pax + cargo). These will affect the Single-aisle
numbers also. About 200 Tankers will be added.
_
5. CASE STUDIES AND COST
IMPLICATIONS
We consider a set of scenarios as illustrated in
Fig.33. Depicted are possible routes (a, b and c) and
tanker base locations.
(a) Based at Anchorage
North America to Asia could utilise AAR
operations based at Anchorage. This is one of the
busiest International air cargo airports, with 2.15
Million Tonnes handled in 2005. This gives an idea
of the scale of operations passing through / over
Anchorage. Typical distances are Tokyo to
Anchorage, about 3000 nm and Anchorage to New
York, 2935 nm.
(b) Europe to Australia
This would allow an airliner to depart, for
example, from London with a full complement of
passengers and freight and fly non-stop to Sydney.
It could take off using de-rated thrust, climb quickly
to best cruising altitude and use AAR to achieve a
direct flight. Avoiding a technical stop would help
in potentially halving the life-cycle costs and
extending its service life.
This case follows the example of the 9000nm
aircraft potentially saving 40% fuel.
(c) US West Coast to Australia
West coast USA to Australia could use the old
“Flying Clipper” routes of PAA - Honolulu, Guam,
Nadi, etc as tanker bases. Typical distances in this
region are Los Angeles to Honolulu, 2220 nm and
Nadi to Sydney 1710 nm. The early “Flying
Clippers” pioneered such routes.
An Example with Freighters, B747F & B767F
The B747-400F, operating close to Pt B
(MTOW), can carry a payload of 123,000 lb over
7,200 nm. At reduced TOW, it can carry twice that
payload over 3600. The B767-300F, at Pt A, carries
123,000 lb over 3,300 nm. Using various
combinations of aircraft and payloads we note, in
Table 2, fuel savings afforded by AAR. Tanker fuel
has been taken into account, RT = 4.
Refuelling the B767-300F with 88,451 lb and
later ‘topping-up’ with 16,082 lb is not the most
efficient scenario or use of tankers. Greater savings
could be achieved with alternative arrangements,
e.g. taking off light and refuelling to maximum
capacity twice, or naturally, more efficient aircraft.
In addition to the DOC estimates we currently
employ for civil passenger aircraft, it would be
useful to have some idea of two associated tanker
costs. The first of these is the tanker operating cost
per hour. This could be derived from military
figures with a conversion to civil operations. The