Go Back  PPRuNe Forums > Flight Deck Forums > Tech Log
Reload this Page >

“SPEED, SPEED, SPEED” Warning

Tech Log The very best in practical technical discussion on the web

“SPEED, SPEED, SPEED” Warning

Old 20th Feb 2018, 15:30
  #1 (permalink)  
Thread Starter
 
Join Date: Oct 2015
Location: 43N
Posts: 257
“SPEED, SPEED, SPEED” Warning

Anybody know why AB decided to call this warning by that name? Wouldn’t it have been more accurate to call it, “POWER, POWER, POWER” since it is a power (low energy) issue rather than a speed issue?

I think I have heard that warning maybe three times over the past seven years, one of which was when flying the transition to 5R at MMMX. The co-pilots response was to increase selected speed by 10 knots. Ofcourse that was the wrong response. Which got me thinking about the human factors aspect of AB naming this warning, “SPEED, SPEED, SPEED” when it is really a power issue.

A little nit picking day for me here at home
CaptainMongo is offline  
Old 20th Feb 2018, 15:33
  #2 (permalink)  
 
Join Date: Dec 2002
Location: Where the Quaboag River flows, USA
Age: 68
Posts: 3,349
Get slow coming aboard the ship, the LSO will call, “POWER, POWER”; your idea has merit.
galaxy flyer is offline  
Old 20th Feb 2018, 16:03
  #3 (permalink)  
 
Join Date: Sep 2016
Location: USA
Posts: 673
For a non Airbus guy, can you guys say what causes this warning to come on?
Vessbot is offline  
Old 20th Feb 2018, 17:33
  #4 (permalink)  
 
Join Date: Oct 2009
Location: UK
Posts: 965
I think I have heard that warning maybe three times over the past seven years, one of which was when flying the transition to 5R at MMMX.
I guess SPEED SPEED makes sense as you call out the error when calling deviations, eg 'Bank Angle', 'Pitch', 'Glideslope'. Lowering the nose will increase the speed and silence the warning, add power to improve the energy state, but it's a very significant alert which is telling you to increase your speed.

No offence, but you must be doing something wrong, you'll hear that warning right before the protections kick in, so why are you pushing the aircraft that far, or allowing it to be pushed that far? Surely it's the sort of thing you'd only hear once in your life and then never again as you'd be scared to death by it? Or is it seen in some other way in your airline? Why would you be flying below VLS in normal operations?

For a non Airbus guy, can you guys say what causes this warning to come on?
When you've got half or more of the flaps out, it basically shouts SPEED SPEED when you're flying slower than VLS (which is a speed equal to VREF on final approach), there are a few more specific conditions but essentially, it's just telling you you are flying FAR too slowly.
giggitygiggity is offline  
Old 20th Feb 2018, 17:57
  #5 (permalink)  
 
Join Date: Sep 2016
Location: USA
Posts: 673
Ok thanks, I figured it would be something like that, but thought it might also be something more complicated due to the OP's request.

If the warning is that the speed is too low, it seems perfectly reasonable to me that it says "SPEED" and not something else. The warning should be what is wrong, not what a supposed cure might be. In many airplanes, power by itself will only make the speed worse.
Vessbot is offline  
Old 20th Feb 2018, 18:00
  #6 (permalink)  
 
Join Date: Jun 2000
Location: last time I looked I was still here.
Posts: 4,507
B737. I used to teach datums and encourage guys to monitor N1% every so often on approach to anticipate changes when they had unwittingly set the wrong N1% for whatever configuration and manoeuvre was required.
On one occasion, on 3nm finals, I could see that the power set from F25 - F40 was going to cause the speed to decay PDQ. I waited and watched his eyes to see if they were alert. Nothing happened, so I called 'Power' which was where the error lay, but before the speed had decayed below Vref and followed the descending green arrow. His eyes were fixated outside, and without looking inside he reduced power. My follow up hand restored the correct setting and he landed. Afterwards he said that, without thinking, I had meant he had too much power.
I reflected and wondered what would have been better.

"Check power!" Proactive.

wait for speed to decay, "Speed" (SOP) reactive.

"increase power" proactive, but that could have caused a without thought agricultural handful.

"Set 62%" proactive (non SOP.)

"Power" was not an SOP call out, but that was the root cause of what was going to be an error that would have triggered an SOP call out. Being plots were are taught to be proactive. I thought I was being correct, but human nature defeated me.

At least he learnt the lesson and took away the need to check more than the damned FD and looking outside. Energy management has various parameters under our control.
RAT 5 is offline  
Old 20th Feb 2018, 18:17
  #7 (permalink)  
Thread Starter
 
Join Date: Oct 2015
Location: 43N
Posts: 257
Giggit...

The warning has nothing to do with airspeed. It independent of protections. It has nothing to do with VLS, this warning can trigger at any airspeed within its reporting envelope. The warning indicates thrust is limited. If flying AT off, increase thrust, if flying AT on, you must push the TL's past the climb detent.

“A low energy warning alerts pilots when aircraft energy is insufficient to achieve a climbing flight path through pitch control alone. The “SPEED, SPEED, SPEED” voice alert repeats every 5 seconds while the condition exists. Thrust must be increased to achieve a climbing flight path. The low energy warning is computed by the FACs. It is available inconfigurations 2, 3, and FULL and is based on aircraft configuration, airspeed deceleration rate, and flight path angle.”

Last edited by CaptainMongo; 20th Feb 2018 at 18:37.
CaptainMongo is offline  
Old 20th Feb 2018, 19:38
  #8 (permalink)  
 
Join Date: Aug 2005
Location: ME
Posts: 239
Originally Posted by Vessbot View Post
For a non Airbus guy, can you guys say what causes this warning to come on?
Too low speed, of course😎
Romasik is offline  
Old 20th Feb 2018, 19:44
  #9 (permalink)  
 
Join Date: Aug 2005
Location: ME
Posts: 239
Originally Posted by CaptainMongo View Post
Anybody know why AB decided to call this warning by that name? Wouldn’t it have been more accurate to call it, “POWER, POWER, POWER” since it is a power (low energy) issue rather than a speed issue?

I think I have heard that warning maybe three times over the past seven years, one of which was when flying the transition to 5R at MMMX. The co-pilots response was to increase selected speed by 10 knots. Ofcourse that was the wrong response. Which got me thinking about the human factors aspect of AB naming this warning, “SPEED, SPEED, SPEED” when it is really a power issue.

A little nit picking day for me here at home
This is to bring your attention to low speed condition. Then it’s up to you - to push it down or to increase power. The latter can potentially aggravate situation due to pitch up moment.
Romasik is offline  
Old 20th Feb 2018, 20:35
  #10 (permalink)  
 
Join Date: Oct 2013
Location: UK
Posts: 51
CaptainMongo speaks the truth.

Only heard it once, and on that occasion, the speed was still well clear of Vls. With a flat pitch attitude turning into the wind on base, our FPA steepened rapidly without a corresponding speed increase as we hit a leeside rotor. I.e. we lost energy, rather than traded it...

The alert sounded before a pitch adjustment was made. ATHR was waking up, responded sufficiently. It is called the "low energy" alert for a reason.

Its all in the FCOM DSC section, and worth a brief anywhere one might mention "terrain induced windshear" or similar.
Smokey Lomcevak is offline  
Old 20th Feb 2018, 22:15
  #11 (permalink)  
 
Join Date: Aug 1998
Location: Ex-pat Aussie in the UK
Posts: 5,331
Originally Posted by Vessbot
For a non Airbus guy, can you guys say what causes this warning to come on?
An aural low-energy “SPEED SPEED SPEED” alert, repeated every 5 s, warns the pilot that the aircraft’s energy level is going below a threshold under which he has to increase thrust, in order to regain a positive flight path angle through pitch control.

It is available in Configuration 2, 3, and FULL. The FAC computes the energy level with the following inputs:
‐ Aircraft configuration
‐ Horizontal deceleration rate
‐ Flight path angle.

The aural alert is inhibited when:
‐ TOGA is selected, or
‐ Below 100 ft RA, or
‐ Above 2 000 ft RA, or
‐ Alpha-floor, or the ground proximity warning system alert is triggered, or
‐ In alternate or direct law, or
‐ If both radio altimeters fail.

During deceleration, the low-energy aural alert is triggered before alpha floor (unless alpha floor is triggered by stick deflection). The amount of time between the two alerts depends on the deceleration rate.
So, the alert only applies below 2000' RA. Typically it turns up on the base or final turn, and usually as the pilot overbanks to capture the next leg. Basically, if you pull back on the stick and there's no "zoom climb" left (speed you can trade for pitch) the aircraft says "no es bueno, kemosabe". Keep pulling and it will give you TOGA thrust regardless (an autothrottle feature known as "Alpha Floor").

en it’s up to you - to push it down or to increase power.
Of course, to increase power is not intuitive in an airbus. Pull the throttles back to disconnect, and then push them forward.

Which is a lot to think of, if you're in that situation.

So the solution is to select (pull) 160kts on downwind, to ensure that you have enough energy on base and final, rather than allow the aircraft to drift the speed back to the minimum (as it will do on managed (automatic) speed).

Last edited by Checkboard; 20th Feb 2018 at 22:51.
Checkboard is online now  
Old 20th Feb 2018, 23:11
  #12 (permalink)  
 
Join Date: Feb 2008
Location: In the Old Folks' Home
Posts: 408
Too Slow!

Shouldn't the call be, "TOO SLOW, TOO SLOW, TOO SLOW!
Smilin_Ed is offline  
Old 20th Feb 2018, 23:45
  #13 (permalink)  
 
Join Date: Jun 2007
Location: Wanderlust
Posts: 2,985
Which got me thinking about the human factors aspect of AB naming this warning, “SPEED, SPEED, SPEED” when it is really a power issue.
My guess is it can be seen it's a warning for approach and landing configurations. Airbus design philosophy is to use available automation. So with ATHR available it's not a thrust issue as thrust would already be at CLB. So it is change of flight path to get the correct speed. Taking thrust levers out of CLB for more thrust has been stopped by Airbus.
vilas is offline  
Old 21st Feb 2018, 00:17
  #14 (permalink)  
 
Join Date: Oct 2009
Location: UK
Posts: 965
CaptainMongo


I know that technically it is independent of protections, but without reacting to it, the next thing you're probably going to see is Alpha Floor which means you've really cocked up. My reading says that "if the aircraft decelerates at 1 kt/sec, and: - The FPA is -3 ̊, the alert will trigger at approximately VLS -8, - The FPA is -4 ̊, the alert will trigger at approximately VLS -2.", therefore for practical purposes, the warning is based on speed. I appreciate that it may call SPEED SPEED at speeds higher than VLS, but I can't see why it should do that under normal operations. Either way, it also would seem odd that it would call out SPEED SPEED if it wasn't telling you to increase speed. Still doesn't explain how you've managed it 3 times in 7 years when getting in that position means you're manoeuvring with inappropriate speeds, or am I still missing something? I know it can occur when the FDs are not being followed, eg a situation where you're in THR IDLE/OP DES and you pitch above the FD bars (not flying in SPEED mode), not sure why you'd be doing that unless you were actively trying to have a chat with the boss? Otherwise, what are you doing turning near or below VLS? If as the others say, it's a result of windshear or rotor effects etc, you've selected an inappropriate speed for the turn in those conditions, you'd be foolish to be anywhere near VLS unless you're flying in a straight line even on a nice day. My airlines policy is not to fly below green dot whilst clean, S speed with flaps 1 and F speed/managed Vapp with all the goodies GS mini gives you, it keeps you safe for the all sensible reasons. I don't mean to appear obtuse, it just seems like a pretty odd thing to hear on a regular basis.
giggitygiggity is offline  
Old 21st Feb 2018, 00:56
  #15 (permalink)  
 
Join Date: Jun 2000
Location: Australia
Posts: 4,164
At least he learnt the lesson and took away the need to check more than the damned FD and looking outside. Energy management has various parameters under our control
Agree about the addiction of flight directors. They are one of the main factors IMHO of the poor rates of instrument scan one frequently observes during simulator training. Being locked on to keeping the twin needle centred requires intense concentration and scan skills soon degrade. That is why many pilots are frightened of turning off the FD and looking foolish.

With regard to the SOP calls in some airlines of "Speed" to caution the PF of undesired out of tolerance IAS indications.

Some operators prefer a call of "Speed low" or Speed high." This at least gives the PF an indication of the direction of speed error. It also has the advantage of picking up an erroneous airspeed problem quickly, if one ASI disagrees with the others. Same principle with a call of "Altimeter." Better to say "Altimeter High" or "Altimeter Low."

"Sink Rate" is yet another vague call. Usually said on final approach.
"Sink Rate high" implies urgency which in the case of below 500 feet on short final is true

Last edited by Centaurus; 21st Feb 2018 at 01:09.
Centaurus is offline  
Old 21st Feb 2018, 02:38
  #16 (permalink)  
 
Join Date: Mar 2012
Location: Dark Side of the Moon
Posts: 1,068
Is simply brings your attention to the wayward parameter, BANK, PITCH, SPEED all direct your attention to the appropriate instrument. POWER POWER might make you look at the N1 or EPR gauges which won't help, if you look at the IAS then you will recognise the condition and should do something about it.
Ollie Onion is online now  
Old 21st Feb 2018, 03:34
  #17 (permalink)  
 
Join Date: Mar 2002
Location: Seat 0A
Posts: 8,144
"Sink Rate" is yet another vague call. Usually said on final approach.
"Sink Rate high" implies urgency which in the case of below 500 feet on short final is true
I hope that, when we hear "Sink Rate" on final as part of an SOP call, we don't have to think about whether s/he meant low or high? Let's not get carried away... What does the GPWS call?
Capn Bloggs is offline  
Old 21st Feb 2018, 03:43
  #18 (permalink)  
 
Join Date: Jan 2015
Location: Near St Lawrence River
Age: 50
Posts: 198
By definition Speed, speed, speed is a warning about the low state of energy, about decaying of the kinetic energy, which is 1/2*m*speed^2. The flight instructor would warn the student in the same way about dangerously low speed condition, thenafter the student realizes that he has to add more power or to relax the pitch up (in a tight turn for instance).
_Phoenix is offline  
Old 21st Feb 2018, 13:16
  #19 (permalink)  
 
Join Date: Aug 1998
Location: Ex-pat Aussie in the UK
Posts: 5,331
My airlines policy is not to fly below green dot whilst clean, S speed with flaps 1 and F speed/managed Vapp with all the goodies GS mini gives you, it keeps you safe for the all sensible reasons.
If you are at F speed and make a 90º turn onto final then a very small overbank will have you into the "SPEED SPEED" regime. The aircraft isn't smart enough to look ahead at the flight path and see that you will be manoeuvring - that's what pilots are for. Blind reliance on the managed speed "keeping you safe" gets pilots into trouble. I would imagine that the poster who has seen this "three times in seven years" was also relying totally on managed speed.

Taking thrust levers out of CLB for more thrust has been stopped by Airbus.
I beg your pardon?
Checkboard is online now  
Old 21st Feb 2018, 13:30
  #20 (permalink)  
 
Join Date: Jan 2001
Location: Around the world.
Age: 40
Posts: 604
I suspect Vilas is referring to phase advance which used to be allowed, moving the thrust levers above the climb gate for a short period of time to temporarily get man thrust / MCT until you click it back into climb when Athr will reengage. Good for 'lazy' autothrust / low energy situation, not so good below 100'
tom775257 is offline  

Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service - Do Not Sell My Personal Information -

Copyright © 2021 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.