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Canada Rouge at Montego Bay

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Canada Rouge at Montego Bay

Old 23rd Aug 2019, 04:53
  #81 (permalink)  
 
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Originally Posted by pfvspnf View Post
Until the FAF then they selected FPA, and for some reason pulled OPEN CLIMB
A bit late to this thread but I do have a question. Why would you use FPA for this approach when Final App can be used for a VOR approach. Or do people tend to just use one or the other as they are both just as effective.
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Old 24th Aug 2019, 14:45
  #82 (permalink)  
 
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Originally Posted by IcePack View Post
Misd.
Interesting about fully manual Flt in an AB. Take manual thrust for an example thrust idle to max is about 5 inches of movement, so adjusting thrust has to be done with finess. You can't just give the thrust levers an inch like you can on a Boeing.
You can move the throttles an inch, or a fraction of an inch, if you so desire. But you bring up an interesting point - throttle/thrust lever travel and relative sensitivity. We can use manual thrust and should always verify, by checking the N1 gauges, what the response was. The only time that's inappropriate is once you're very low and about to, or in, the flare. I switching from Boeing to AB and caught a nasty sink rate just prior to touchdown with relatively low time on the AB. I used muscle memory to push the AB thrust levers up....WHOA!....too much power! Landed ok and made the somewhat tight midfield turnoff (no parallel taxiways). The amount of power I had received based on the throttle movement threw me off. I think the Boeing throttles gave less power per inch/degree of travel vs the AB thrust levers. Or put another way, the AB engines give more power for the same amount of throttle/thrust lever travel. I base that observation on more time in the aircraft using manual thrust and from measuring the throttle/thrust lever travel on the Boeing 737 vs Airbus 320. I wonder if anyone knows the actual answer? (TDracer??).
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Old 24th Aug 2019, 14:55
  #83 (permalink)  
 
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Can’t answer the question regarding the amount of thrust versus lever travel. However there is quite a difference between the length of the thrust levers on both aircraft. The thrust levers on the Boeing are considerably longer and hence why your hand makes a larger input to achieve the same lever travel versus the stubby levers on the Airbus.
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Old 24th Aug 2019, 14:59
  #84 (permalink)  
 
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Originally Posted by CEJM View Post
Can’t answer the question regarding the amount of thrust versus lever travel. However there is quite a difference between the length of the thrust levers on both aircraft. The thrust levers on the Boeing are considerably longer and hence why your hand makes a larger input to achieve the same lever travel versus the stubby levers on the Airbus.
Thanks. In the heat of the battle it wasn't something that had crossed my mind and I reverted to using what I thought was an appropriate amount of power based on my Boeing experience, which turned out to be too much on the AB. Like you mention part of the equation might be the longer arm of the Boeing throttles so your hand is traveling farther to get the same degree of travel.
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Old 24th Aug 2019, 21:11
  #85 (permalink)  
 
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Originally Posted by misd-agin View Post
You can move the throttles an inch, or a fraction of an inch, if you so desire. But you bring up an interesting point - throttle/thrust lever travel and relative sensitivity. We can use manual thrust and should always verify, by checking the N1 gauges, what the response was. The only time that's inappropriate is once you're very low and about to, or in, the flare. I switching from Boeing to AB and caught a nasty sink rate just prior to touchdown with relatively low time on the AB. I used muscle memory to push the AB thrust levers up....WHOA!....too much power! Landed ok and made the somewhat tight midfield turnoff (no parallel taxiways). The amount of power I had received based on the throttle movement threw me off. I think the Boeing throttles gave less power per inch/degree of travel vs the AB thrust levers. Or put another way, the AB engines give more power for the same amount of throttle/thrust lever travel. I base that observation on more time in the aircraft using manual thrust and from measuring the throttle/thrust lever travel on the Boeing 737 vs Airbus 320. I wonder if anyone knows the actual answer? (TDracer??).
I'm afraid I don't know much about the Airbus thrust levers - other than they are short and don't move very far as compared to Boeing. I am familiar with most of the Boeing thrust levers - although the 737 is the exception. The 757/767 forward thrust levers are 12.25 inches long (axis of rotation to center of the knob), and have an angular travel of 56 degrees (except the 767-400, which uses the 777 levers). Going strictly to FADEC meant the thrust levers could be made a little smaller with less travel, since you didn't need to account for the cable backlash and lost motion, so the 747-400/-8 and 777 use similar levers, 11.25 inches long and 50 degrees of angular travel. Due to an FAA mandate, the 787 uses a completely different thrust lever assembly than the 777 (really, really dumb in my opinion - the 777 thrust lever module was the best Boeing ever did, far better than the POS they ended up with on the 787 - which is sadly also going to used on the 777X) - but the 777 and 787 are dimensionally similar. I believe the 737 NG levers are similar to the 777, but I don't know specifics, and I'm reasonably sure the thrust levers on the MAX are unchanged from the NG.
In all cases, there is ~2 degree 'flat' at both ends (takeoff and idle) to insure slight miss-rigging won't affect the ability to get either takeoff power or idle. Max climb power is always at about 80% of the forward thrust lever travel.
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Old 25th Aug 2019, 16:53
  #86 (permalink)  
 
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"I'm afraid I don't know much about the Airbus thrust levers - other than they are short and don't move very far as compared to Boeing." Thanks for the reply. A bit of negative transfer going from Boeing to Airbus when I had to 'grab a bunch of power' fighting a big sinker just prior to touchdown. Grabbing a Boeing fistful of power in an Airbus resulted in more power than I expected. Live and learn.

Last edited by misd-agin; 25th Aug 2019 at 17:27.
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Old 25th Aug 2019, 17:29
  #87 (permalink)  
 
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Thanks for making us all a bit smarter - "In all cases, there is ~2 degree 'flat' at both ends (takeoff and idle) to insure slight miss-rigging won't affect the ability to get either takeoff power or idle. Max climb power is always at about 80% of the forward thrust lever travel."
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Old 25th Aug 2019, 17:33
  #88 (permalink)  
 
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Originally Posted by punkalouver View Post
A bit late to this thread but I do have a question. Why would you use FPA for this approach when Final App can be used for a VOR approach. Or do people tend to just use one or the other as they are both just as effective.
Previously TRK/FPA was used for all NPAs. Then Airbus changed to flying NPAs with vertical guidance ILS like with HDG/VS with FDs.
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Old 26th Aug 2019, 13:42
  #89 (permalink)  
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Originally Posted by Capot View Post
...I was there when, still sitting in the flight deck at Muharraq , the Captain of a B707-338C, operating as QF739 on February 21, 1969 explained how he regained control after the aircraft went out of control over the Arabian Gulf on route to Bahrain at FL350 and M 0.81, dived inverted, rolled, probably went supersonic momentarily (not recorded accurately due to compressibility issues at the pitots) ) recorded +4.57G and - 0.63 G, and lost 19,000 ft. "I realised that we had finally entered a spin", he said, "so I recovered it like I would a Tiger Moth. No big deal." And off he went with the crew for a stiff drink in the Gulf Hotel. We found soap stuck to the ceilings in the toilets. Crews would be trained to recognise a situation where they have lost effective control of their aircraft because they do not understand what the automatics are up to, and/or when something is obviously seriously wrong and getting worse, and to use the button to recover, stabilise, whatever, using their basic flying skills, if they have any.
The Qantas Boeing 707-338C VH-EAB was operating the scheduled service Sydney - London as QF739 on February 21, 1969. On the sector Bangkok - Bahrain it had 72 people on board. On departing Bangkok the aircraft was approximately 20 tonnes under its maximum take-off weight. It was this fact that probably saved everyone from the events that were to shortly unfold. It was suggested by Boeing, on investigating the incident, that had the aircraft been significantly heavier then she would probably not have survived the stresses that were inflicted on the aircraft's structure.

The passenger cabin was in darkness and the Tech and Cabin Crew had started rotating for their meal breaks. The Captain was back on the flight deck, having finished his meal break while the First Officer was in the Crew Rest Area, just starting his.

The aircraft was stabilised in normal cruise mode, travelling at 35,000 feet and M 0.81. The Autopilot was flying a radial away from Jiwani, a small town near the Pakistani border with Iran towards a waypoint out over the Arabian Gulf.

There was no visual horizon.

Unbeknown to the pilots, the aeroplane had a recent history of problems with the Captain's Horizon Direction Indicator, or Artificial Horizon (HDI), which was ultimately attributed to a faulty Bendix gyroscope.

The post incident investigation recorded that the Captain had glanced away from his main instruments, down and to his right, at the centre pedestal.

When he looked up he immediately saw that his HDI was indicating that the aircraft was in a 30 degree uncommanded bank to the right.

Without cross checking the First Officer's instrument or the standby Horizon between the two pilots, the Captain corrected for this non existent bank. The aircraft immediately responded by rolling to the left robustly, became inverted and dived away towards the ground.

In the next 40 seconds the aircraft lost 19,000 feet of altitude. The Flight Data Recorder (FDR) would later disclose that the aircraft had attained a maximum speed of M 0.93 although the feeling was that it had been briefly supersonic, but compressibility issues around the pitot tubes had caused the Airspeed Indicators to under read the actual speed.

The FDR recorded a maximum positive 'G' figure of 4.57 while a significant negative 'G' figure of 0.63 was recorded.

There were a couple of 'porpoising' manoeuvres undertaken as the Captain and Second Officer recovered the jet, and given the speeds and 'G' indications, it was fortunate they didn't have the wings and tail fail in the process. As it was, there was a significant rippling of the fuselage skin around the rear doors and on the overwing surfaces. A considerable number of the inspection panels had 'popped' all over the skin, with their spring loaded locks still in the 'locked' position.

Boeing estimated that at the time of the incident the aircraft weighed about 96,000 kgs.

Multiplying this by the positive 'G' vale of 4.57 indicates that for periods during the 'upset' (such is the euphemism used for events of this nature) the aircraft 'weighed' some 440,000 kgs or nearly 40 tonnes more that a fully laden Boeing 747-400.

The aircraft was successfully landed at Bahrain Airport without further incident. The Tech and Cabin Crew were stood down as is normal following this sort of misadventure while the passengers were dispersed to Gulfair and British Airways to continue their journey. Teams of engineers were dispatched from Boeing and Qantas Engineering at Mascot to assess whether the aircraft was still airworthy.


The Bahrain Bomber Incident

I didn't know the Capt but I know the SO of that event, and the report. Airplane didn't spin...it did an impressive spiral dive however. At that time the aircraft did not have a comparator between attitude indicator other than pilot monitoring. IIRC while the B747 had comparators early on, it wasn't early enough for the AI 855, a B742 off the end of 27 at Mumbai, and it wasn't insistent enough for the KAL 8509, a B742F out of Stanstead. IN both of these cases, the FE was aware of the instrument failure, and despite hving a comparator in the second event, it was not enough on the night to save the flight from the disorientation of an erroneous AI.


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