usabusdriver
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- Aug 12, 2007
- 205
- 113
PI,
The difference as has been discussed is that a Boeing will tell the pilot that they are going to exit the envelope and an Airbus will not allow it.
Here is a scary scenario that can happen to you that was thought out after the AF loss. A loss of pitot input to the ADRs that does not give a fault at the end of takeoff followed by a second pitot failure that again does not give a fault shortly after takeoff. In this low level scenario following the pitch/power for unreliable airspeed will have the crew lose control of the aircraft in about 2 and a half minutes because of the normal law override for Vmo.
I watched it unfold in the sim. The instructor told us we were going to get unreliable airspeed indications and to follow the QRH procedures. We recognized the unreliable airspeed right after thrust reduction. We received NO ecam warnings. We performed the QRH procedures for below FL 250 and above thrust reduction still in Config 1+F. AP AT OFF 10 degrees pitch. Climbing at a rate of approximately 1800 fpm. Reading the novel that is the QRH for unreliable airspeed interupted by CWC for flap overspeed. Got that silenced. Back to reading. Approaching 4500 feet or so airspeed indications are 340kts increasing rapidly. Normal law protections kick-in and a vicious feedback cycle begins. Full forward side stick and pitch is rapidly increasing causing a rapid increase in climb rate causing a rapid increase in indicated airspeed causing further increase in pitch. Onset is quite aggressive and loss of control very quick. I rolled the aircraft maximum as the pitch took off to lower the nose, yet we lost control as the trim was working fast and the increased loading and angle of attack stalled the aircraft without sufficient altitude to recover. A real eye opener to say the least. I mean to tell you that it happens FAST. The simulator is NOT the aircraft, but wow. I had the stick full forward, fully to the side and my foot to the floor when the sim froze and I kind of held that for few seconds as the disbelief was still being processed.
The scenario as I remember it is a rather remote possibility, run through a swarm of bees on takeoff roll to block pitot and then hit birds for additional blockage. The automation that keeps us "in the envelope" has a failure that is subtle with no ADR ecams, and therefore in NORMAL law, causes loss of control when close to the ground because performance exacerbates the problem. We might see some sort of procedural change when the powers to be fully digest this type of scenario.
The difference as has been discussed is that a Boeing will tell the pilot that they are going to exit the envelope and an Airbus will not allow it.
Here is a scary scenario that can happen to you that was thought out after the AF loss. A loss of pitot input to the ADRs that does not give a fault at the end of takeoff followed by a second pitot failure that again does not give a fault shortly after takeoff. In this low level scenario following the pitch/power for unreliable airspeed will have the crew lose control of the aircraft in about 2 and a half minutes because of the normal law override for Vmo.
I watched it unfold in the sim. The instructor told us we were going to get unreliable airspeed indications and to follow the QRH procedures. We recognized the unreliable airspeed right after thrust reduction. We received NO ecam warnings. We performed the QRH procedures for below FL 250 and above thrust reduction still in Config 1+F. AP AT OFF 10 degrees pitch. Climbing at a rate of approximately 1800 fpm. Reading the novel that is the QRH for unreliable airspeed interupted by CWC for flap overspeed. Got that silenced. Back to reading. Approaching 4500 feet or so airspeed indications are 340kts increasing rapidly. Normal law protections kick-in and a vicious feedback cycle begins. Full forward side stick and pitch is rapidly increasing causing a rapid increase in climb rate causing a rapid increase in indicated airspeed causing further increase in pitch. Onset is quite aggressive and loss of control very quick. I rolled the aircraft maximum as the pitch took off to lower the nose, yet we lost control as the trim was working fast and the increased loading and angle of attack stalled the aircraft without sufficient altitude to recover. A real eye opener to say the least. I mean to tell you that it happens FAST. The simulator is NOT the aircraft, but wow. I had the stick full forward, fully to the side and my foot to the floor when the sim froze and I kind of held that for few seconds as the disbelief was still being processed.
The scenario as I remember it is a rather remote possibility, run through a swarm of bees on takeoff roll to block pitot and then hit birds for additional blockage. The automation that keeps us "in the envelope" has a failure that is subtle with no ADR ecams, and therefore in NORMAL law, causes loss of control when close to the ground because performance exacerbates the problem. We might see some sort of procedural change when the powers to be fully digest this type of scenario.