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BA A321 tailstrike.

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BA A321 tailstrike.

Old 4th Aug 2015, 00:51
  #21 (permalink)  
 
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A RAD ALT on the tail link into the pitch computer and a filter than resists further pilot input.

No aircraft works that way.

No a/c worked that way until AB, F16, FBW, Stealth a/c.
Really? With a RAD ALT on the tail linked into the pitch computer?

You learn something every day.
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Old 4th Aug 2015, 02:06
  #22 (permalink)  
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Originally Posted by RAT 5
No a/c worked that way until AB, F16, FBW, Stealth a/c. They have built in anti-stall pitch limiters; alpha floor etc.
What you are referring to is not in effect on the ground or take-off/landing. The way FBW actually works and what you heard in the bar obviously is not the same.

Originally Posted by Cough
How about this, from Boeing
Boeing has removed the tails skid from new build 777s to reduce weight and drag. Removal from existing aircraft is also available via service bulletin, the tail skid system weighs more than a passenger. Typically you will see one 777 tail strike a year in Narita.
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Old 4th Aug 2015, 07:03
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[AP/FD RA] Standard on Std 1.9 A320 too now
It's an option, and an expensive one at that. Don't know if any airline has actually gone for it.
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Old 4th Aug 2015, 07:25
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swh - Yup, the SKID has gone, but the tail strike prevention software is operational. Reread the article... Or even this from the 777 flight control section from SmartCockpit

Tail Strike Protection
During takeoff or landing, the PFCs calculate if a tail strike is imminent and decrease elevator deflection, if required, to reduce the potential for tail skid ground contact. Activation of tail strike protection does not provide feedback to the control column.
*IF installed!*

Last edited by Cough; 4th Aug 2015 at 07:36.
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Old 4th Aug 2015, 07:57
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The tail skid assembly that Boeing installed on the 737 is positioned for the tail strike on takeoff. Remember on t/o the aircraft is rotating around the main gear so any potential tail strike will be in a fixed position. On landing the tail skid is irrelevant as in the flare the aircraft is now rotating around its c of g. This tail strike (as most are) was on landing and they are the ones that do the serious damage.
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Old 4th Aug 2015, 13:23
  #26 (permalink)  
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Yup, the SKID has gone, but the tail strike prevention software is operational.
Read you own quote "reduce the potential", not eliminate. There are still multiple 777 tailstikes a year. Most of the tailstrikes at Narita are related to environmental conditions, not what the pilots is asking the aircraft to do.
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Old 4th Aug 2015, 15:47
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No aircraft works that way.
Completely wrong there. The E190 employs a very similar system called Tail Strike Avoidance (TSA). The fly-by-wire system limits pitch angle to 8 degrees nose up during take-offs, landings and go-arounds if an impending tail strike is sensed.

Protection during landing is based on the height above ground level (calculated using two radio altimeters) and protection during take-off is based on vertical speed.
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Old 5th Aug 2015, 04:29
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When the A340-600 was introduced it was the longest airliner airframe, and it had anti-tailstrike software.
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Old 5th Aug 2015, 12:20
  #29 (permalink)  
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Originally Posted by Localiser Established
Completely wrong there. The E190 employs a very similar system called Tail Strike Avoidance (TSA). The fly-by-wire system limits pitch angle to 8 degrees nose up during take-offs, landings and go-arounds if an impending tail strike is sensed.

Protection during landing is based on the height above ground level (calculated using two radio altimeters) and protection during take-off is based on vertical speed.
True to a point however, it will not cater for gross mishandling. If the E195 is the same it didn't limit pitch but reduced elevator authority based on a number of factors but you could still whack the tail if you tried hard enough.
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Old 6th Aug 2015, 19:03
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Alternative Option

How about equipping the Airbus range with a wide angle HUD and fly the approach on Angle of Attack? Include a CCIP dot in the picture and train pilots to fly a constant Alpha approach with a brief check in pitch as the rad alt counts down through 20 feet.

Works in the FJ world believe it would work on the Bus.
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Old 7th Aug 2015, 05:58
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Originally Posted by ZFT
Our friends in TLS aren't helping matters. Despite 1100+ A321s being built and another 1500+ on order, they refuse to produce a datapack for the A321 so currently all FSTDs are A320 only.
This seems very strange. Could you confirm ZFT?

From the report:
The non-discovery of the damage during the engineer's external inspection for the turn round is difficult to understand.
This is the primary function of a tail skid, to visually give a clear indication of a tail strike. They are not sturdy and therefore not designed to protect the aircraft unless the force of the strike is minimal.
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Old 7th Aug 2015, 12:25
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SWH

A RAD ALT on the tail link into the pitch computer and a filter that resists further pilot input.
"No aircraft works that way."
Cough beat me to it.

B777-300 have just such a system and have removed the tail skid as a result.

The semi-levered MLG also helps.

It also has a contact sensor just in case.
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Old 7th Aug 2015, 12:45
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I believe the 777-300 TSP system works by computing pitch angle/rate, rather than being directly driven by a Rad Alt in the tail.
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Old 7th Aug 2015, 14:09
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The Embraer E190/195 has had tail strike prevention in the FBW software for as long as I can remember.
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Old 7th Aug 2015, 14:45
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Tail Skid purpose

The purpose of the tail skid on the 737.400 is being oversimplified here. The tail skid had dimples which told you if you had just touched with no damage, there were many of those. There was a crush cartridge which told you of a bad one, you or someone else, so there was an element of warning/training in that system
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Old 8th Aug 2015, 01:36
  #36 (permalink)  
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vapilot2004
Quote:
Originally Posted by ZFT
Our friends in TLS aren't helping matters. Despite 1100+ A321s being built and another 1500+ on order, they refuse to produce a datapack for the A321 so currently all FSTDs are A320 only.

This seems very strange. Could you confirm ZFT?
I confirm.

Not just the A320 family either.

For the A330 you have single choice of an A320-200 datapack, the A350 an A350-800 datapack etc..

So for operators such a CX and VNA (and others) who operate or will operate A330-300, A350-900/1000 and A321s only, their FSTDs are not fully representative.
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Old 9th Aug 2015, 00:31
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ZFT:

I confirm.

Not just the A320 family either.
This seems unreasonable. My guess would be because the FBW system tends to mete out flight dynamics differences between aircraft sub-types, although that leaves operation in Direct Law hanging.

Yesterday, a Check Airman stated his informed thoughts on the matter and the reasons given were: proprietary data concerns, regular flight control software updates rendering previous flight dynamics models obsolete, how Airbus prefers to train thoroughly for the base model, then focus on differences training, and finally and most importantly (to the airline), cost.

Any of this ring true for you, ZFT?

Last edited by vapilot2004; 9th Aug 2015 at 01:20. Reason: Added CA's thoughts
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Old 9th Aug 2015, 00:59
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i just want to intervene either guys..
I've just flown the A321 Simulator from
lufthansa, D-AIRN, its a company choice if you order your aircraft with tailstrike protection which is definetly highlighted in the pfd with symbols or you order a gpws warning which warns you from a potentially tailstrike "pitch pitch" My a321 didn't had both of these systems. And tailstrikes in an a321 are nothing special.. the a321 is the most difficult aircraft in the a320-line or in general in the complete airbus series. Just my 2 cents..
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Old 9th Aug 2015, 02:41
  #39 (permalink)  
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yannickue

That particular FSTD is around 20 year old. Airbus in those days would produce a datapack for a specific tail number and IIRC DLH and Swissair ordered specific A321s. However today Airbus will not longer supply.
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Old 9th Aug 2015, 02:57
  #40 (permalink)  
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vapilot2004,

I concur that the Airbus policy is to train thoroughly for the base model, then focus on differences training and indeed they have stated this at various conferences. Many operators have also strongly disagreed with Airbus at said conferences, especially those that only operate A321s.

I would disagree re cost as Airbus generate massive revenues (and profit) from Datapacks and the additional tests (whether flight or engineering) to support an A321 variant would be really quite insignificant and as pointed out by yannickue, they did provide A321 data in the past. (Many of the tests within the current datapack are years old and are as applicable now as when initially produced).

The issue of regular flight control updates is already addressed by bi annual datapack updates which currently Airbus provide FOC for 10 years although I understand this is being reduced to 5 years.

Don't quite understand the proprietary data concern.
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