“Tower-Contractor
1 EXPEDITE!”
More
runway tales...
In
the recently published articles entitled,
“Airport Tales” and
“Mayday. Mayday”
- Airport memories 25 years on- the
writer has drawn upon personal, hands-on experience to share with
readers aspects of airport maintenance that are not usually in the
public domain, together with some anecdotes that are entirely unique.
This is not for any purpose of self- aggrandisement, it is simply
that few have made the transition from a Highways and Airport
maintenance related career to that of writing, the latter proving to
be a wonderful medium wherewith to share memories that would
otherwise be lost as time unfolds. This particular article is likely
however, to be the last such piece but even if this proves to be so,
only snap-shots of the 'behind the curtain' world of 'live' airport
maintenance are revealed.
One of the biggest headaches that airport
operators face in relation to aircraft safety relates to the
maintenance of runway skid resistance values (SRV's). Runways are
constructed and laid-out to provide for reciprocal operations and
therefore have two thresholds and two areas known as TDZ's or
Touch-Down Zones; this is due to the fact that aircraft take off and
land into the wind, rather than with the wind behind or across the
aircraft for the purpose of maximising aerodynamic 'lift'. A TDZ is
typically 500 metres in length and full runway width, however the
predominant area of concentration is 10 metres either side of the
localiser (centre-line) by 500 metres (or longer) in length.
When an aircraft lands, a number of
functions occur simultaneously or very close to simultaneously; let
us imagine a Boeing 747 for this example. Approaching at around
160-180 knots, in full landing flap configuration with landing gear
extended, at the point of touch-down the nose comes up and the
aircraft settles down; as the main landing cart (all 16 wheels) locks
down, the anti-lift flaps or spoilers deploy dumping the mass of the
aircraft onto those huge wheels whilst on touch-down, the flight
management systems initiate a one-touch-2 second braking moment
whilst the aircraft engines are placed into reverse-trust mode. This,
together with supplementary braking, causes a considerable amount of
rubber to be laid down in the touch-down zones which has the effect,
in due time, to substantially occlude runway surface texture and skid
resistance values fall accordingly.
Readers may recall from the
article which recalled anecdotes from Damascus in 1999, that the full
length of the runways had become compromised by rubber deposits as
aircraft had become forced to land deeper and deeper due to SRV
occlusion. In fact, a KLM pilot confided to the writer at the time,
that were they to encounter rain at Damascus, a diversion to Beirut
would have been inevitable on grounds of safety!
 |
| An example of Captive Hydrology removing rubber deposits. This was not the actual machine as used on the project concerned. |
There are various ways of solving the
problem of rubber build-up and the removal thereof, but most involve
the closure of a runway which is inevitably costly and time consuming
with operational penalties adding to the headache. One of the most
effective in terms of time and cost and because there is no
requirement to close runways is the use of Captive Hydrology. This is
a one-vehicle, one-pass completed process which combines the use of
very high water pressure and powerful vacuuming to recover the water
and rubber debris. This also has the added benefit of removing FOD'S
(foreign object debris) simultaneously. The writer was a one of the
pioneers of the technique in airport operations, as a matter of
interest.
 |
| RAF Brize Norton: Rubber deposits can be picked out from this view. |
At RAF Brize-Norton in 2001, we had been
tasked to carry out a rubber removal operation during a continuous
process at a weekend. 22000 square metres had to be cleaned during
what we understood was a 'closed runway' regime and in theory, this
would be relatively straight-forward. Where things went wrong was,
that on arrival at the control tower for a pre-works briefing, it
became 'fairly clear' that the runway was anything but 'closed'. The
first hint of which being when this columnist, a VHF licensed RT
operator, was handed a radio and call signs were agreed (Contractor
1). The RAF runway was fully-operational this weekend after all! But
with Captive Hydrology, we can shut down and vacate a runway leaving
it safe to function within minutes and so typically, ATC can call up
with something like the following:
“Contractor
1-Tower: Traffic inbound 6 miles longs; vacate runway”
“Tower-Contractor
1: roger that: Vacate runway”
(Sometimes
the instruction would include the perhaps euphemistic verb
'expedite'!)
 |
| RAF C-17 Globemaster III |
But our Austrian operator (Hans) and
'yours truly' got on with things and during the night, we were treated
to a variety of military comings and goings interspersed with
'tower-contractor' banter over the VHF radio with no small amount of
humour being spared, all of which served to make the night-day shift
all the more bearable. But inevitably, something had to go awry; at
one point, a call came into vacate, but the call was not heard [this
can happen] in which case ATC resorted to a 'highly technical'
back-up procedure which basically involved flashing the runway edge
lights! EXPEDITE! Barking ones instructions to Hans who panicked, he
was unable to get the machine out of operational gear (hydrostatic)
so we were limited to 10 KPH forward travel! We nevertheless vacated
but the aircraft (a Boeing 757-200 charter plane) then proceeded to
follow us down the RET (rapid exit taxiway) en route to stand.
'Hansie' could see the aircraft right up behind us to the extent that
once again, 'eye lids were batting at both ends of his physiology',
whilst RT banter between ATC, the 757 pilot and 'yours truly' was
hilarious! When we were finally able to turn off and the aircraft
revved up and passed us, there was a moment of various lights being
flashed (by the 757) and time honoured hand signals between the first
officer and this columnist who, as he pens this memoir, is grinning
and chuckling, 13 years on!
Given the enhanced nature of on-site
operational requirements, the pair of us opted to work through
without a break and successfully completed our operations in 18 hours
(phew). On completion, the writer signalled ATC thus:
“Tower
-contractor 1. All TDZ operations fully complete and runway vacated.
The runway is yours and incidentally, many thanks for the air-show.”
Back came the reply:
“Contractor
1- Tower. Many thanks; we aim to please!”
There followed our usual de-brief in
SATCO's office much of which cannot be related here, however whilst
our respective standard requirements were seen through to the letter,
the humour was almost aerobatic.
Live runway maintenance operations
involve very high levels of planning and concentration on all sides
of the contractual relation with all parties being devoted to our
mutual primary duty, that of safe airport operations. In 47 years of
combined Highway and Airport maintenance works, never was so much
fun, happiness and exhilaration gained, from the most dangerous and
critically important operations and locations as was gleaned from
airport operations at home and overseas, and these will never be
forgotten by this now seemingly 'grounded' Asphalt Surfacing Consultant who has embraced semi-retirement with all due alacrity. (edited 16/5/2022)
By
Chris Green
Beşparmak Media Services
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