Tropic Workhorse

It was unusual however in that we made an intersection takeoff with a roll of less than 500 metres and three knots of tailwind – the sort of figures generally associated with much smaller aircraft.

According to Ian Phillips, the Dash 7 could take off at this speed right up to max auw of 19,958 kg.

For fuel conservation and time-saving Air Nuigim Dash 7s routinely do intersection and downwind takeoffs, without straining crew or aircraft by pushing things close to their limits.

Takeoffs are usually undertaken with 15 degrees of flap rather than 25, which can result in the aircraft becoming second segment limited during climb out.

The Dash 7 is remarkable for its ability to operate into and out of strips with muddy or otherwise dubious surfaces with very few restrictions.

Rabaul Airport, for instance, breaks up with monotonous regularity in wet weather, but the Dash 7 can use only a small part of the runway surface, enabling the airport to remain open for it while it is closed to F27s previously operated by Air Nuigini, which use most of the runway length.

Neither is the Dash 7 bothered by sloping strips, which are common in Papua New Guinea. On Goroka’s 2. 7 per cent sloping strip it can operate comfortably at maximum all up weight with 10 knots of tailwind and a temperature of plus 28°C.

Engine out performance is also impressive.

Ian Phillips recalls an occasion when with an engine feathered at 15,500 ft, the aircraft weight at 17,600 kg and three engines at max continuous, fuel flow was 1160 pounds per hour with a true airspeed of 200 knots.

Normally the Dash 7 trues out at 215-220 knots and the average fuel flow is about 1480 pounds per hour at 15,000 feet or 1440 pounds per hour at 16,000 feet

Air operations in PNG are routinely conducted at ISA (international standard atmosphere) plus 15 °C which creates a significant penalty in any other aircraft in the Dash Ts weight range but has a relatively small effect on it.

‘Most of the strips we operate this aircraft into, it is not limited until the temperature reaches plus 40 °C at sea level, which we never see,’ Ian Phillips said.

‘As the altitude increases the limiting temperature obviously decreases but even in the highlands, temperatures must climb to about plus 26°C before weight restrictions apply. ‘

Following the recent change of Government in Papua New Guinea, a question mark arose for some time over the continued operation of the Dash 7s for Air Nuigini.

The new Government of Mr Somare halted for a time the sale of Air Nuigini F27s and also halted an airport upgrading program initiated by the former Government, which has purchased the Dash 7s.

Annual utilisation of the three-aircraft Dash 7 fleet is currently 6500 hours with some additional charter and cargo work on top of this.

Maintenance and on-time reliability is such that departures free of maintenance-related problems are 98. 7 per cent – the highest in the Air Nuigini fleet.

In one recent month, the Dash 7s earned $64,000 kina in freight charters to Kiunga for the Ok Tedi project alone.

They now operate twice a day into K1unga on cargo services while the low level of the Fly River makes water transport difficult, and scheduled services six times weekly are to start soon.

‘On one flight we uplifted 4. 6 tonnes between Moresby and Kiunga,’ Ian Phillips said.

‘Admittedly we had to go to Mt Hagen, 5350 ft elevation to refuel but no other aircraft in this weight class could do that. There is a Hercules going into Kiunga now and again but the fact that we can operate in the same league as a specialised aircraft like that speaks for itself.

‘No one could fly to Kiunga the way we did because of the takeoff weight limitations imposed on other aircraft at a high altitude step.

‘This aircraft has not got any, unless the temperatures are right up, and you do not find those sorts of temperatures up there. ‘

They believe the Dash 7 is no one-off special aircraft, but rather one which is establishing a new trend in airline flying.

In the UK another Dash 7 operator, Brymon, has been fighting with British CAA to give stol runway clearance so It can provide a commuter service into London, and recently demonstrated landing on a disused wharf in London’s dockland.

In the US, Ransome Airlines operates from stub runways and taxiways at major airports and uses an area navigation system to put them under normal approach and departure paths.

Ian Phillips is not bothered by the possibilities in such circumstances of overshoots or overruns by aircraft using stub runways that intersect with other active runways.

‘With today’s cost of fuel, and airlines looking at more conser vative ways of operating their aircraft, I feel there is more demand on pilots to fly more exactingly.

‘I do not think there is any problem. The safety factor is still built into it,’ he said. They would have to allow for an overshoot if he was doing an instrument approach and coordinate traffic accordingly. There is no question of any danger ever arising from it, but I doubt very much if you will ever see it in Australia.

‘You fly into Honolulu and they will give you eight rights to land on and not to overrun the intersection of 94 because there is a DC-10 coming in which also has a landing clearance and will cut straight in front of you.

‘They put the onus on the pilot and you cannot just sit there and say “I am not going to land” or “I am going to overshoot” because they have traffic going all the time and when you get a clearance it is like a machine gun. ”

An Omega navigation system has recently been installed in all Air Nuigini Dash 7s and is used in routine operations, including operation into highlands airfields such as Mendi, Wapenamanda (5800), Telefomin, Tari, where there are no nav aids.

Pilots initially had doubts about how effective the system would be in the highlands but tests gave impressive accuracy, even though the Australian Omega station was not in operation at that time.

Although it had been a beautiful morning when we took off from Moresby, we were soon flying over what looked like a solid 8/8 cloud cover.

Air Nuigini pilots have to be adept however at finding legal holes in clouds and we were soon approaching Kiunga, main staging base on the Fly River for the Ok Tedi project, flying Just under the low ceiling.

Kiunga is only 1000 ft AMSL but the strip is very narrow with a not very good surface which deteriorates when it is wet, which is most of the time.

The rather touchy border with Indonesian West is only 18 nm west and charts bear the charming but not exactly reassuring notation: ‘Jungle covered terrain believed not to exceed 200 ft elevation. ‘

We did not land but spent some time circling low over the staging areas on the river bank to give our marine-oriented passengers a look.

The usual technique for finding an airfield in bad weather is to position overhead then find a hole in the cloud and let down until a visual search can be made, then fly a bad weather circuit just under whatever ceiling exists.

Omega is substantially reducing the problems encountered m this type of operation, although pilots are still legally required to descend under VFR and acquire the strip visually before making an approach.

‘A lot of hard work has been taken out by the advent of the Omega system,’ Ian Phillips said

‘We still have to do a bit of scouting around at times to pick things up visually. ‘

Peter Sharpe added: ‘Most of the strips we operate into are equipped with radio aids, like Hagen, which has an NDB and DME, but due to the terrain you have no instrument approach into Hagen whatsoever. You have the lowest safe altitude of 16,400 feet and the only way to get in there is visual.

‘You can position yourself over the top and from local knowledge of the various valleys and gaps you would normally be able to get in.

There Is a tower there so you are not totally ignorant of the weather.

‘Goroka for instance does not have a NOB or DME – only a radio station which we use for position checks.

‘Omega will not assist in these areas unless the nav aids fail when it allows overhead positioning so that cloud breaks or other visual cues can be found for a visual approach.

The Dash 7s are also equipped with an RCA Colour radar which is very good in the terrain mapping mode.

“In areas like going to Gurney (Milne Bay) you have a harbour off which the airstrip runs with no nav aids lan Phillips said. The radar is brilliant for ground mapping and orientating you over the harbour. Although there are legal limitations on the extent to which this can be used, with a little local knowledge of the lie of the land it can be very useful for accurately locating an airfield in marginal weather. ‘ Both pilots said they found the cockpit an excellent workplace -information presentation was very good, as was ease of access to controls and the noise level was lower than an F27, ‘This is better laid out. After a few sectors in an F27, you become fatigued because you are reaching around the cockpit much more. Peter Sharpe said.

“Here we have larger cockpit windows and more natural light so it is not as claustrophobic, Pressurisation for instance is more accessible compared to the F27 where it can only be worked by the first officer.

‘There is not one thing the captain cannot do by staying in his seat. ” We stopped around over Daru at the mouth of the Fly River for a while, looking at the proposed site of a new bulk export port, then for the return to Moresby they agreed to demonstrate a STOL landing.

In a stol approach with 45 degrees of flap, the Dash 7 adopts a steep nose-down attitude. To set a comfortable landing in this configuration is ‘not difficult, but you have to work at it,’ says Lan Phillips.

‘When you go to flare you have to rotate through about 15 degrees from a nose-down to a nose-up attitude. Therefore you can, if you are a little below Vref, just fall out of the sky on rotation and give yourself a firm landing to say the least. ” At the lower outboard corner of both the pilot and co-pilot’s windscreen is a small vernier-scale speed indicator so the flying crew member can keep his eyes outside and see at a glance whether the needle is centred, indicating he is exactly on landing speed our case 76 knots, or 1. 3 VS.

The speed indicator is operated in conjunction with air data computer which knows weight of aircraft and it varies automatically with flap change settings.

The lowest aircraft weight of 14,515 kg gives a Vref (reference speed for landing) of 71 knots which is 10 knots slower than a DC-3 landing speed.

Our landing weight was about 16,330 kg which gave a Vref of 76 knots, which is still five knots slower than a DC-3.

“Vref is 1. 3 VS (stall speed) so the Dash 7 lands at 30 per cent above stall speed which in this configuration would be 49 knots,’ Ian Phillips said.

By comparison, the stall speed on an F27 with flaps down at low weight at 16-1700 kg is about 73 knots.

‘So it is quite a safe aircraft. If you have to manoeuvre in bad weather in valleys or anything like that it has fantastic manoeuv ring capabilities because of its slow speed down a bit of flap and you can charge around all day at 100 odd knots. ” On the stol approach, the support pilot calls height and sink rate (which is not to get above 1200 fpm- anything below this means speed is below Vref and power must be increased.

Cockpit dialogue during the final approach went something like this:

Phillips: ‘Flap 45 thank you.’
Sharpe: ‘Flap 45 selected, we have been cleared to land.’
‘1000 feet- Vref plus two.’
‘On speed 500 feet to touchdown.’
‘Speed plus three. ‘ ‘On speed-200 feet to height-on speed-minus two- on speed-50 feet to touchdown.’

Touchdown was tolerably senile about what you would expect in your average DC-9 although there was no doubt we had arrived.

We touched down about 1500 feet down the runway, pulled up in about 450 feet using mostly reverse thrust with just a touch of braking, and turned off comfortably onto the second taxiway. When I remarked on the stopping performance Peter Sharpe, in the midst of after-landing checks, replied: ‘He was not even trying two and three to feather-you could actually land this aeroplane in an area where you could not take it off again.”

Phillips adds: ‘You can get a smoother touchdown if you continue the flare and gently touch it down but the object of the exercise is to pick an aiming point and put it down on that.”

Complaints about airline flying becoming dull and repetitive and pilots becoming little more than ‘systems managers’ certainly do not apply in Air Nuigini’s Dash 7 operations. My thanks to the two pilots and others who helped to arrange the trip.