EMB-145 hydroplanes off rwy in Ottawa...
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D and F, Yes its true that stop-go/ balanced field distances are calculated without using reverse, but to fly in Canada in the winter without reverse is about as dumb as disconecting the ABS on a new car or driving all year on summer tires {or tyres, if a Brit} No, its not Winter here right now but this doesnt change the point that with reverse, instead of residual thrust pushing, the outcome would most likely have been a non event, add to no reverse the third world aspects of CYOW {no TDZ lights, no C/L lights, no Catt 2 or 3, drops at the end of two runways, no overun protection poor rubber removal from Rw 25/07} we are headed for a major loss of life here given our climate, its a pity the media and local politicians dont seem to understand this . Our airports policy in Canada is totally flawed, the decline I observe on a weekly basis with reductions of basic services and closure of strips will, in time result in only major centres having reliable, safe air service, its time to re visit the whole privitization mess and stop building supermarkets on active airports, along with the odd gas stations at the end of runways or excursions such as this will result in headlines for sure!
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Barbi, "Cracking Aircraft?" Yup, this one has some very expensive looking cracks in it now, Forward fuse bent all to hell, cockpit floor up about ten inches, gear trunion broken of, major distortion around first five frames, cracking indeed!I wonder how this stacks up against the cost of reverse thrust?
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CBC this AM is reporting that the young lady who gave a very accurate and clear report on what she heard on the tower freq and a clear description of events during this over run has been kicked of the "Airport Watch" team, Benoit, the airport manager claims that they have a "no talk" rule for these folks, she claims she has never signed such a form, I prefer to go with her version, it seems the heat may be getting a bit too much for Benoit now that the media is clueing in on the third world conditions at CYOW and money spent on waterfalls and frills rather than improving safety, just wish the media would do some REAL reporting on this, but the local CBC is totally gutless and CTV not much better, its hard to remember that this nation was once a world leader in anything!
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Not having reversers would make a decision for an aborted landing easier... i guess they might have encountered poor braking on the RWYs end, maybe due to rubber, wich on wet conditions is quite scaring, my guess.
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There is no performance advantage with the reversers if memory is correct.
Now here's something I had forgotten about the 145's system (it was mentioned on another bb): If you have weight on wheels but no wheel speed (due to hydroplanning) then the logic dictates that a wow fault is present and brakes, TRs and spoilers are locked out, because the logic assumes the aircraft is flying. TRs wouldn't have mattered anyway, it seems.
(Time to hit the systems book again -
)
The company TSA which owns the aircraft had the reverses removed for cost savings.
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Let's clarify something here,
TR's are not credited in stopping distance, but when you are on ice, or hydroplaning, they are about the only device that stops the aircraft. So they do have a real world effect. Caution in crosswinds of course.
In other words, runway grooving, or TR's, or both, could have saved this airframe.
TR's are not credited in stopping distance, but when you are on ice, or hydroplaning, they are about the only device that stops the aircraft. So they do have a real world effect. Caution in crosswinds of course.
In other words, runway grooving, or TR's, or both, could have saved this airframe.
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Squawk 7777
Correctamundo re spoilers. If you're out for a spot of aquaplaning the a/c helpfully leaves the spoilers flush due zero wheel speed.
The wheel brakes are inhibited until a few seconds afer touchdown so you get-briefly, but it seems to last a while- no brakes and no spoilers.
I think this is why it felt to me like we'd sped up!
Correctamundo re spoilers. If you're out for a spot of aquaplaning the a/c helpfully leaves the spoilers flush due zero wheel speed.
The wheel brakes are inhibited until a few seconds afer touchdown so you get-briefly, but it seems to last a while- no brakes and no spoilers.
I think this is why it felt to me like we'd sped up!
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The emergency brake is never locked out, but if you are riding water then thats not gonna help much either. Time for some runway grooves I think.
D and F
GROUND SPOILER
AIRPLANE OPERATIONS MANUAL
The Spoiler Control Unit (SCU) automatically performs ground spoiler opening, without pilots' interference. The SCU enables the ground spoilers to open whenever the following conditions are met:
− Airplane on the ground. − Main landing gear wheels running above 25 kt. − Both engines thrust lever angles set to below 30° or both engines N2
below 56%.
If any of those conditions is not met, the ground spoilers will not open. A status indication is presented on the EICAS to indicate that the spoilers are open or closed. If a failure is detected, a caution message is presented on the EICAS.
AIR/GROUND INDICATION SYSTEM
LANDING GEAR AND BRAKES
Air/ground indication is determined by a system that detects landing gear shock absorber compression and relays information to the landing gear electronic unit for gear control. The system consists of five weight-on-wheel proximity switches. Two of them are installed on each main landing gear leg and one on the nose landing gear leg.
The Landing Gear Electronic Unit (LGEU) processes the main landing gear proximity switches’ signals information in four independent channels and controls various equipment operations. Logic processing includes the position signal and its validity. If all proximity switch signals are valid, four signals are processed to assure that at least three signals indicate identical status for releasing the air/ground signal output.
Should one proximity switch signal be invalid, the logic will process the remaining three signals so that at least two indicate the same status. If a second proximity switch is invalid, the two remaining signals are processed only if both send the same signal. Disagreement between these two remaining proximity switches causes the Landing Gear Electronic Unit to de-energize the channels and provide a default output signal.
The nose landing gear proximity switch signal is sent only to the thrust reverser logic (if installed) and steering control.
TOUCHDOWN PROTECTION
The touchdown protection system inhibits brake actuation before the main wheels spin up during landing. Brake actuation will be allowed only after 3 seconds from the latest touchdown or after the wheels have spun-up to 50 kt. In bouncing landings, the countdown is reset after each runway contact.
Touchdown protection is provided by the brake system receiving signals from main landing gear weight-on-wheel proximity switches. If one landing gear proximity switch fails at the air position, the brake system will operate normally. However, if both proximity switches fail at the air position, braking capacity will be available only for wheel speeds above 10 kt.
Below 10kt, a loss of the main brake capacity will occur, but emergency braking is still available.
EMERGENCY/PARKING BRAKE SYSTEM
The emergency/parking brake system is used when parking the airplane or when the normal braking system has failed. The emergency/parking brake system is mechanically commanded and hydraulically actuated. It is totally independent of the BCU, so it has none of the normal braking system protections.
THRUST REVERSERS
OPERATION LOGIC
AIRPLANE OPERATIONS MANUAL
Each FADEC will command Maximum Reverse thrust on ground only, when the associated thrust reverser is deployed and associated thrust lever is requesting reverse thrust whenever either of the following conditions are met:
- Airplane on the ground indication from both main landing gears, and main landing gear wheels running above 25 kt, or
- Airplane on the ground indication from both main landing gears and from nose landing gear.
During landing, when the Thrust Levers are set to below IDLE, the FADEC commands reverse thrust only after the Thrust Reverser doors (both engines) are completely deployed. If the Thrust Lever is requesting forward thrust, the FADEC will command IDLE thrust if the associated engine thrust reverser indicates that there is a ̈not stowed ̈ or a ̈deployed ̈ condition.
If one engine is inoperative or one thrust reverser is not deployed, the FADEC of the operative side will only command Reverse Thrust if the associated Thrust Lever is requesting reverse thrust and the Thrust Lever of the affected side is set to IDLE. Such a feature is provided to avoid uncommanded thrust asymmetry.
D and F
GROUND SPOILER
AIRPLANE OPERATIONS MANUAL
The Spoiler Control Unit (SCU) automatically performs ground spoiler opening, without pilots' interference. The SCU enables the ground spoilers to open whenever the following conditions are met:
− Airplane on the ground. − Main landing gear wheels running above 25 kt. − Both engines thrust lever angles set to below 30° or both engines N2
below 56%.
If any of those conditions is not met, the ground spoilers will not open. A status indication is presented on the EICAS to indicate that the spoilers are open or closed. If a failure is detected, a caution message is presented on the EICAS.
AIR/GROUND INDICATION SYSTEM
LANDING GEAR AND BRAKES
Air/ground indication is determined by a system that detects landing gear shock absorber compression and relays information to the landing gear electronic unit for gear control. The system consists of five weight-on-wheel proximity switches. Two of them are installed on each main landing gear leg and one on the nose landing gear leg.
The Landing Gear Electronic Unit (LGEU) processes the main landing gear proximity switches’ signals information in four independent channels and controls various equipment operations. Logic processing includes the position signal and its validity. If all proximity switch signals are valid, four signals are processed to assure that at least three signals indicate identical status for releasing the air/ground signal output.
Should one proximity switch signal be invalid, the logic will process the remaining three signals so that at least two indicate the same status. If a second proximity switch is invalid, the two remaining signals are processed only if both send the same signal. Disagreement between these two remaining proximity switches causes the Landing Gear Electronic Unit to de-energize the channels and provide a default output signal.
The nose landing gear proximity switch signal is sent only to the thrust reverser logic (if installed) and steering control.
TOUCHDOWN PROTECTION
The touchdown protection system inhibits brake actuation before the main wheels spin up during landing. Brake actuation will be allowed only after 3 seconds from the latest touchdown or after the wheels have spun-up to 50 kt. In bouncing landings, the countdown is reset after each runway contact.
Touchdown protection is provided by the brake system receiving signals from main landing gear weight-on-wheel proximity switches. If one landing gear proximity switch fails at the air position, the brake system will operate normally. However, if both proximity switches fail at the air position, braking capacity will be available only for wheel speeds above 10 kt.
Below 10kt, a loss of the main brake capacity will occur, but emergency braking is still available.
EMERGENCY/PARKING BRAKE SYSTEM
The emergency/parking brake system is used when parking the airplane or when the normal braking system has failed. The emergency/parking brake system is mechanically commanded and hydraulically actuated. It is totally independent of the BCU, so it has none of the normal braking system protections.
THRUST REVERSERS
OPERATION LOGIC
AIRPLANE OPERATIONS MANUAL
Each FADEC will command Maximum Reverse thrust on ground only, when the associated thrust reverser is deployed and associated thrust lever is requesting reverse thrust whenever either of the following conditions are met:
- Airplane on the ground indication from both main landing gears, and main landing gear wheels running above 25 kt, or
- Airplane on the ground indication from both main landing gears and from nose landing gear.
During landing, when the Thrust Levers are set to below IDLE, the FADEC commands reverse thrust only after the Thrust Reverser doors (both engines) are completely deployed. If the Thrust Lever is requesting forward thrust, the FADEC will command IDLE thrust if the associated engine thrust reverser indicates that there is a ̈not stowed ̈ or a ̈deployed ̈ condition.
If one engine is inoperative or one thrust reverser is not deployed, the FADEC of the operative side will only command Reverse Thrust if the associated Thrust Lever is requesting reverse thrust and the Thrust Lever of the affected side is set to IDLE. Such a feature is provided to avoid uncommanded thrust asymmetry.
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Aeromexico Connect 145 runway excursion earlier this year. Non-Grooved & Wet RWY and no TR. Plane had enough energy left to travel for 200m in mud.
Incident: Aeromexico Connect E145 at Tijuana on Jan 21st 2010, went off runway on landing
JetPhotos.Net Photo » XA-WAC (CN: 145255) Aeroméxico Connect Embraer ERJ-145LU by GeorgeMxl
rcl
Incident: Aeromexico Connect E145 at Tijuana on Jan 21st 2010, went off runway on landing
JetPhotos.Net Photo » XA-WAC (CN: 145255) Aeroméxico Connect Embraer ERJ-145LU by GeorgeMxl
rcl
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There is a general misconception that grooved runways are always better than other surface treatments under wet conditions. A surface with large aggregate asphalt will have the same runway friction characteristics on wet/flooded surfaces as a grooved surface with the same average macrotexture. There are examples of overruns on wet, grooved runways. If grooved runways are not maintained well, or the depth and spacing is as such that the average macrotexture is still low, they will not help you getting better friction on a wet surface.
Prof. Airport Engineer
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Wet weather friction
The three main aspects of good wet weather friction are geometry (crossfall, gradient), macrotexture, and microtexture. The matter is complex and a systematic approach demands all three aspects receive attention. It can be likened to the legs of a 3-legged stool - if one leg is missing, the stool is unstable. Just what the facts are at Ottawa, I don’t know. But the Embraer 135 overrun at George South Africa in December was aquaplaning due to deficiencies in all three. The interim accident report is on the CAA website in South Africa:
AircraftAccidentReportsIndex
and look for the latest updates below the annual accident reports – 7 December 2009 ZS-SJW
decurion's comment about grooving presents a view that could be mis-interpreted. What Decurion says is not, in itself, incorrect:
However the issue is that most asphalt surfaces have LESS macrotexture than a grooved surface, and crucially, less than the ICAO recommended minimum of 1.0mm. That is why, generally speaking, grooving makes a difference and an ungrooved asphalt runway is always looked at with suspicion that its macrotexture is below standard (unless or until proven otherwise).
Cheers
Overrun
AircraftAccidentReportsIndex
and look for the latest updates below the annual accident reports – 7 December 2009 ZS-SJW
decurion's comment about grooving presents a view that could be mis-interpreted. What Decurion says is not, in itself, incorrect:
A surface with large aggregate asphalt will have the same runway friction characteristics on wet/flooded surfaces as a grooved surface with the same average macrotexture
Cheers
Overrun
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Yes, lots of chuckles about this around CYOW, the airframe is now in the First Air hangar, its gona need a fair bit of duct tape to fix, Red Green is on his way. {For non Canucks, Google it}
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The GASR (Group of Aerodrome Safety Regulators) proposed the following (see GAR Subpart F – Physical Characteristics):
(f) Runway surface texture
(1) The average surface texture depth of a runway should be more than 1.0 mm, or the surface should be grooved.
(2) Grooves that should meet the requirement for good breaking action when the surface is wet, should be cut with a tool that leaves a clean cutting edge, the width of each groove should be 5 – 7 mm and the spacing between grooves should be approximately 125 mm.
(3) The average surface texture depth and/or grooving of a runway should be given in the AIP for the aerodrome together with data on surface type (class A, B, C, D or E).
(4) Surface texture shall be measured periodically. If the runway is grooved, the grooves shall be checked periodically for evenness and depth.
GASR does not limit these requirements to new surfaces (like ICAo now does) but also considers existing runways (if I read the GAR text correctly). This GASR work will be adopted by EASA for their Aerodrome Regulation.
(f) Runway surface texture
(1) The average surface texture depth of a runway should be more than 1.0 mm, or the surface should be grooved.
(2) Grooves that should meet the requirement for good breaking action when the surface is wet, should be cut with a tool that leaves a clean cutting edge, the width of each groove should be 5 – 7 mm and the spacing between grooves should be approximately 125 mm.
(3) The average surface texture depth and/or grooving of a runway should be given in the AIP for the aerodrome together with data on surface type (class A, B, C, D or E).
(4) Surface texture shall be measured periodically. If the runway is grooved, the grooves shall be checked periodically for evenness and depth.
GASR does not limit these requirements to new surfaces (like ICAo now does) but also considers existing runways (if I read the GAR text correctly). This GASR work will be adopted by EASA for their Aerodrome Regulation.