PPRuNeUser0131
16th Aug 2020, 04:51
Another good article from an old USA magazine about to be dispatched to the re-cycling bin. Greasers when landing a 727? Not likely by Len Morgan, Flying June 1993
Landing is the most interesting phase of flight in any aircraft. In some ways, it is the most challenging, particularly for a pilot unhappy with anything less than the delicious slide of rubber on concrete so aptly described as “painting it on.”
The smoothness with which an aircraft can be transferred from sleek flying machine to ungainly ground vehicle depends on several factors, most of them beyond the pilot’s control. Take its landing gear: The DC-4 had large tyres and long struts; hold it a foot off the runway with the nose up a few degrees and it would settle ever so softly onto the ground, making you look better than you were.
But “soft” landing gears are heavy, require large storage wells and therefore annoy designers whose last concern is flattering pilots. So, they made the DC-6 noticeably stiff-legged. You could pull off a good landing in a -6, but a “greaser” was rare. The same was true of the Connie. The Electra was downright humbling; for gear it seemed to have cast-iron wheels and I-beam struts. A remarkable plane in many respects, it could loosen your fillings on arrival no matter how hard you tried. The 707, on the other hand, would often reward an attentive driver with a gentle touch-down. (And the 747 was an absolute delight, I would learn a few years later.)
I’d wondered how Boeing’s trijet would compare. What an absolutely marvellous airplane! The 727 was more pilot-friendly from the first day than any other transport in my logs. It was easy to learn. The ground school was a snap and my flight training was completed days ahead of schedule without the customary simulator warm-up. Not everyone, however, found the transition to the “Three-Holer” to go as smoothly. This is not to say I was sharper than average. Far from it; I am a slow learner. I breezed through 727 training simply because I had already flown the 707.
Qualifying on that brute was something else. It was almost three times the weight of the Electra I had been flying. It was ponderous, accelerated slowly even at maximum power and hurtled along at the bottom of descent with power at idle. Unless you stayed miles ahead of it on letdown, there was no option but to request a 360 while speed dwindled, a common embarrassment among newcomers to jet flying.
Something we piston drivers never appreciated until we lost it was the braking provided by idling props. The turbojet developed considerable shove even with thrust levers back against the stops. Precise speed on final was extremely important. The 707 floated 1,000 feet for every 10 knots of excess speed over the fence. This could get you into trouble at a marginal field like Kansas City Municipal when braking action was reported as fair to poor.
The 707 was heavy on the controls until you learned to trim it. And, of course, we had to cope with its (then) astounding weight and blazing speed using the same instruments and navigation gear installed on piston equipment. The only computers in early jet cockpits were between the pilots’ ears. Yet after 200 hours I felt completely at home in the new marvel and wouldn’t have swapped it for a seat on the Stock Exchange.
This background provided a tremendous edge during transition to the 727, which is not to say it was a scaled-down of its big sister. Boeing’s new baby had rear-mounted engines, two rudders, four ailerons, 14 spoiler sections, 26 flap panels, nosewheel brakes and a tail skid. But the hydraulic, electrical and fuel systems were nearly identical to the 707’s, as was the cockpit layout.
In everything I had previously flown, powerplant performance was monitored as much by listening as by what the gauges reported. The 727 cockpit was eerily quiet; in contrast, you were scarcely aware of engine thunder even at takeoff thrust. This took some getting used to.
In flight the 727 was a dream, light on the controls and delightfully responsive. Descent, approach and landing techniques came easily to anyone with 707 experience. When a radar controller requested an expedited descent, you eased back on the “speed brake” lever that deployed the flight spoilers and you came down like a load of sand. You could lose altitude at 4,000 fpm and faster of you dropped the gear. The same trick in a 707, while safe and legal, caused an uncomfortable shuddering that made nervous passengers look out the windows.
Descent and approach posed no problems once you got the feel for the 727. Our descent drill was: idle thrust and Mach.80 from cruising level to 320 knots, then 320 to 10,000 feet, below which the speed limit was 250. The flight engineer noted weight and computed a reference speed (Vref), which was 1.3 times stalling speed with landing flaps. Depending on weight, Vref was 115 to 125 knots.
At five to 10 miles from the outer marker, flaps were extended “on schedule”. At 200 knots, the “Flaps 2“ handle position extended a pair of leading-edge slats on each wing and dropped trailing-edge flaps two degrees. At 190 knots, “Flaps 5“ dropped all remaining leading-edge slats and flaps and extended trailing-edge flaps to five degrees. At 160 knots “Flaps 15“ was selected and at 140 you moved the flaps control to “Flaps 25“. The idea was to cross the outer marker with flaps extended 25 degrees and speed nailed on 140 knots. There was nothing to it after a bit of practice.
When the glideslope came alive you dropped the gear and landing flaps, reduced speed to Vref plus 10 and tidied up the cockpit for arrival. Small power adjustments thereafter kept speed and sink rate where they belonged from outer marker to airport – and it was important that they were closely monitored.
Decaying airspeed or increasing sink rate had to be immediately set right, particularly below 500 feet. Any combination of low speed, excessive rate of descent or spooled-down engines was potentially lethal. There was more than one disastrous 727 undershoot before this deadly combination was fully appreciated. You had to stay well ahead of the 727 at all times which, of course, means it’s no different from any other airplane, large or small.
One thing we old piston drivers had to learn was that jets don’t touch down on the numbers. Instead, you aimed them at a point 1,000 feet down the runway. That seemed like a waste of perfectly good concrete but it made sense in that it prevented a pilot a trifle low from dragging his wheels through the approach lights. The natural urge to “duck under” when breaking out of a 100-foot overcast had to be suppressed.
“Hold what you got” was the ironclad rule regrading descent rate once the runway came into view. (I must digress at this point. I can already hear the hoots of men and women in Africa, South America and polar regions who routinely shoehorn 727s and other jets into short gravel strips where planting the mains is imperative. My admiration for those gutsy troops is unbounded.)
It’s said that a good approach offers the best shot at a good landing and I believe that’s true. So, you had best fly the Three-Holer precisely “on profile,” properly trimmed, with speed and descent rate right on the money down to the runway threshold and ease off the power. What then? If you were landing on one of Portland, Oregon’s incredibly smooth runways and it was wet from recent rain and it was one of your best days, you might just slick it on. But it was foolish to bet on it.
At most airports, our passengers knew when the flight ended. The touch down was firm, though not uncomfortably so, and often produced a short skip. A sudden sink during flare in the stretched 727-200 could sometimes be offset by releasing back pressure on the wheel. This lowered the nose and slowed the descent rate of the rear-mounted main gear, avoiding a jarring arrival. Sounds crazy but it worked. The Three-Holer rarely embarrassed its pilots on landing; neither did it often reward them with a greaser - and that’s a comment not a complaint. You’ll never hear anything but praise from me about Boeing’s magnificent Model 727.
End
Landing is the most interesting phase of flight in any aircraft. In some ways, it is the most challenging, particularly for a pilot unhappy with anything less than the delicious slide of rubber on concrete so aptly described as “painting it on.”
The smoothness with which an aircraft can be transferred from sleek flying machine to ungainly ground vehicle depends on several factors, most of them beyond the pilot’s control. Take its landing gear: The DC-4 had large tyres and long struts; hold it a foot off the runway with the nose up a few degrees and it would settle ever so softly onto the ground, making you look better than you were.
But “soft” landing gears are heavy, require large storage wells and therefore annoy designers whose last concern is flattering pilots. So, they made the DC-6 noticeably stiff-legged. You could pull off a good landing in a -6, but a “greaser” was rare. The same was true of the Connie. The Electra was downright humbling; for gear it seemed to have cast-iron wheels and I-beam struts. A remarkable plane in many respects, it could loosen your fillings on arrival no matter how hard you tried. The 707, on the other hand, would often reward an attentive driver with a gentle touch-down. (And the 747 was an absolute delight, I would learn a few years later.)
I’d wondered how Boeing’s trijet would compare. What an absolutely marvellous airplane! The 727 was more pilot-friendly from the first day than any other transport in my logs. It was easy to learn. The ground school was a snap and my flight training was completed days ahead of schedule without the customary simulator warm-up. Not everyone, however, found the transition to the “Three-Holer” to go as smoothly. This is not to say I was sharper than average. Far from it; I am a slow learner. I breezed through 727 training simply because I had already flown the 707.
Qualifying on that brute was something else. It was almost three times the weight of the Electra I had been flying. It was ponderous, accelerated slowly even at maximum power and hurtled along at the bottom of descent with power at idle. Unless you stayed miles ahead of it on letdown, there was no option but to request a 360 while speed dwindled, a common embarrassment among newcomers to jet flying.
Something we piston drivers never appreciated until we lost it was the braking provided by idling props. The turbojet developed considerable shove even with thrust levers back against the stops. Precise speed on final was extremely important. The 707 floated 1,000 feet for every 10 knots of excess speed over the fence. This could get you into trouble at a marginal field like Kansas City Municipal when braking action was reported as fair to poor.
The 707 was heavy on the controls until you learned to trim it. And, of course, we had to cope with its (then) astounding weight and blazing speed using the same instruments and navigation gear installed on piston equipment. The only computers in early jet cockpits were between the pilots’ ears. Yet after 200 hours I felt completely at home in the new marvel and wouldn’t have swapped it for a seat on the Stock Exchange.
This background provided a tremendous edge during transition to the 727, which is not to say it was a scaled-down of its big sister. Boeing’s new baby had rear-mounted engines, two rudders, four ailerons, 14 spoiler sections, 26 flap panels, nosewheel brakes and a tail skid. But the hydraulic, electrical and fuel systems were nearly identical to the 707’s, as was the cockpit layout.
In everything I had previously flown, powerplant performance was monitored as much by listening as by what the gauges reported. The 727 cockpit was eerily quiet; in contrast, you were scarcely aware of engine thunder even at takeoff thrust. This took some getting used to.
In flight the 727 was a dream, light on the controls and delightfully responsive. Descent, approach and landing techniques came easily to anyone with 707 experience. When a radar controller requested an expedited descent, you eased back on the “speed brake” lever that deployed the flight spoilers and you came down like a load of sand. You could lose altitude at 4,000 fpm and faster of you dropped the gear. The same trick in a 707, while safe and legal, caused an uncomfortable shuddering that made nervous passengers look out the windows.
Descent and approach posed no problems once you got the feel for the 727. Our descent drill was: idle thrust and Mach.80 from cruising level to 320 knots, then 320 to 10,000 feet, below which the speed limit was 250. The flight engineer noted weight and computed a reference speed (Vref), which was 1.3 times stalling speed with landing flaps. Depending on weight, Vref was 115 to 125 knots.
At five to 10 miles from the outer marker, flaps were extended “on schedule”. At 200 knots, the “Flaps 2“ handle position extended a pair of leading-edge slats on each wing and dropped trailing-edge flaps two degrees. At 190 knots, “Flaps 5“ dropped all remaining leading-edge slats and flaps and extended trailing-edge flaps to five degrees. At 160 knots “Flaps 15“ was selected and at 140 you moved the flaps control to “Flaps 25“. The idea was to cross the outer marker with flaps extended 25 degrees and speed nailed on 140 knots. There was nothing to it after a bit of practice.
When the glideslope came alive you dropped the gear and landing flaps, reduced speed to Vref plus 10 and tidied up the cockpit for arrival. Small power adjustments thereafter kept speed and sink rate where they belonged from outer marker to airport – and it was important that they were closely monitored.
Decaying airspeed or increasing sink rate had to be immediately set right, particularly below 500 feet. Any combination of low speed, excessive rate of descent or spooled-down engines was potentially lethal. There was more than one disastrous 727 undershoot before this deadly combination was fully appreciated. You had to stay well ahead of the 727 at all times which, of course, means it’s no different from any other airplane, large or small.
One thing we old piston drivers had to learn was that jets don’t touch down on the numbers. Instead, you aimed them at a point 1,000 feet down the runway. That seemed like a waste of perfectly good concrete but it made sense in that it prevented a pilot a trifle low from dragging his wheels through the approach lights. The natural urge to “duck under” when breaking out of a 100-foot overcast had to be suppressed.
“Hold what you got” was the ironclad rule regrading descent rate once the runway came into view. (I must digress at this point. I can already hear the hoots of men and women in Africa, South America and polar regions who routinely shoehorn 727s and other jets into short gravel strips where planting the mains is imperative. My admiration for those gutsy troops is unbounded.)
It’s said that a good approach offers the best shot at a good landing and I believe that’s true. So, you had best fly the Three-Holer precisely “on profile,” properly trimmed, with speed and descent rate right on the money down to the runway threshold and ease off the power. What then? If you were landing on one of Portland, Oregon’s incredibly smooth runways and it was wet from recent rain and it was one of your best days, you might just slick it on. But it was foolish to bet on it.
At most airports, our passengers knew when the flight ended. The touch down was firm, though not uncomfortably so, and often produced a short skip. A sudden sink during flare in the stretched 727-200 could sometimes be offset by releasing back pressure on the wheel. This lowered the nose and slowed the descent rate of the rear-mounted main gear, avoiding a jarring arrival. Sounds crazy but it worked. The Three-Holer rarely embarrassed its pilots on landing; neither did it often reward them with a greaser - and that’s a comment not a complaint. You’ll never hear anything but praise from me about Boeing’s magnificent Model 727.
End