EFIS - Primary Flight Display (PFD) - Airspeed Display (iFly 747-400)

[@diliptalekar4602]

Fantastic lesson Captain Al! I am a retired heart surgeon(!!!) who obviously belongs to the super-enthusiast category.Had dreamed of becoming a pilot but ended up being a surgeon. Really enjoyed the video & subscribed immediately.Look fwd to devouring the rest of your videos. Thanks! Dilip - from India

[@subsonicflighttraining]

Thanks Dilip, my content is not open heart surgery, so you will have no problem learning from it. Glad you are enjoying it and retirement.

[@The.Chiefman]

Thank you. You answered about 20 questions I had in one tutorial. Great work

[@subsonicflighttraining]

Glad to help!

[@proudbirther1998]

Capt Al, Another well produced video and very informative for Flight Simmers. You have a very good ability to teach how these flight systems function and explain what each symbol means. Thanks again for taking the time to make these videos. They mean a lot to many people that share your love for Aviation, and Airplanes.

[@subsonicflighttraining]

Thanks ProudBirther, I try to put some thought into explaining the given topic, appreciate the comment...

[@christianpilon7725]

thank you Sir for this taken on time to explain .

[@subsonicflighttraining]

Your welcome Christian. hope you enjoy the videos...

[@manoel737]

SUPPERB !!! Thank you very much for your explendid work !

[@subsonicflighttraining]

Your welcome Jorge, glad you enjoyed the video...

[@claudioual8143]

Very Nice, thanks for.

[@subsonicflighttraining]

Your welcome Claudio…

[@nickde6339]

Very clear. Thank you.

[@subsonicflighttraining]

My pleasure...

[@PaulCrooks-x4j]

Again, thanks

[@subsonicflighttraining]

My pleasure!

[@Mikinct]

Great video- very informative. Quick question for yourself or the group here. How does most FMC calculate weight & balance. Meaning, I goto Simbrief, select the plane in my case the 777-200er, I then modify, edit to exact match on empty weight of my plane in the sim to match simbrief version. I print out report and add Gross weight, Zero Fuel Weight to sim FMC. I already loaded the plane to match Simbrief specs with exact Passenger & Cargo= Payload weights etc. My question is if I enter Gross weight my FMC auto calculates ZFW. If I enter ZFW the FMC will autocalculate the Gross Weight. The issue I'm seeing is the numbers do not match my Simbrief report calculations. Again, its only off my a dozen kilograms but I'm trying to understand why & how does the flight sim FMC use for its estimated calculations? any pointers would be appreciated. Thanks in advance....

[@subsonicflighttraining]

The fuel is calculated from the Fuel Quantity Processor by sensors in the tanks that measure volume, temperature, and fuel density. Once you start the engines, CALC fuel is based on Totalizer Fuel up to engine start, then uses Fuel Used via Fuel Flow to derive CALC fuel. PROG PG 1 shows both the Totalizer Fuel and the Calculated Fuel. Totalizer is the sum of all the Fuel in the tanks. We then will always reference our final load sheet to determine the ZFW, your BOW + PAX + CARGO. This ZFW is added to the Current CALC Fuel to come up with GW. We never enter GW to figure ZFW. It is always ZFW to give you GW. If this is off at all by 10-20 kgs, that is basically less than 50 pounds, not a factor at all…

[@pelebar1636]

thank You.

[@subsonicflighttraining]

You bet Pele...

[@andrewbarber8758]

I'm confused. You mention that the green flap speed markers are the minimum maneuvering speed for that flap setting, but then also say the yellow band is the minimum maneuvering speed band. I would expect the flap indicated speed to be the top of the yellow band?

[@subsonicflighttraining]

They are 2 different maneuvering speeds, one references your margin to stick shaker, and the other is based on your VREF 30 speed, based on your present weight. The minimum maneuvering speed, which is the top of the amber band, gives you a 30% margin above stall speed, flaps up or extended. It is referenced as a 1.3G maneuver capability to stick shaker and is displayed when you make the first flap retraction after takeoff. A 30% margin or 1.3G will give you enough margin to make a 25 degree bank turn allowing for a 15 degree overshoot or up to 40 degrees of bank in level flight before encountering stick shaker. This is if you were right at that minimum maneuvering speed, it is a minimum. We really don't want to be at that slow of a speed because reduced maneuver capability exists when you are in that amber band, and if you are slowing more, you will enter stick shaker, warning you of an impending stall. The flap maneuvering speed, on the other hand, is based on your weight and referenced to your VRef 30 speed in increments of +10, 20, 40, 60, and 80 knots. Vref 30 + 80 knots would be the Flaps Up Minimum Speed, VRef30 + 60 would be Flaps 1 Minimum Speed, VRef 30 + 40 would be Flaps 5 Minimum Speed, VRef 30 + 20 knots would be Flaps 10 Minimum Speed, and Vref 30 + 10 knots would be Flaps 20 Minimum Speed, and then with your final Flaps 30 the minimum speed would be VRef 30 + 5 knots up to 20 knots depending on wind additives. On extension or retraction of flaps, our speed will be well above the amber minimum maneuvering band to give us more than adequate margin as we extend or retract flaps. I hope that helps...

[@andrewbarber8758]

@@subsonicflighttraining Thanks for the reply, it definitely helps. In my mind, I am thinking top of amber band is minimum maneuvering speed, flap indicated speed is minimum speed to maintain full maneuvering? Does that sound right? amber band = you shouldn't make any turns, amber to flap speed = be careful with your turns, flap speed and above = good to go.

[@subsonicflighttraining]

@@andrewbarber8758 Yes, you got it. Amber band = you do not want to or have no reason to be operating in that range, reduced maneuvering capability, meaning you will not have at a minimum 1.3G protection. Even at the top of the band and just out of it is too slow, but at least you have 30% above stick shaker protection in a 25 degree bank, level flight, even accounting for a 15 degree overshoot error to 40 degrees. Generally, flap maneuver speeds allow turns up to 25 degrees of bank, unless you are above 680,000 pounds, then the bank angle should be limited to 15 degrees between F1 and UP. Once the flaps are UP, then you should be at a minimum speed of Vref30 + 100 for full maneuvering. That speed is 250 knots commanded by VNAV if you are lighter and greater than 250 knots if heavier. For example if Vref30 + 80 = 162, then VNAV would command a speed of 262 knots after the Flaps are UP below 10,000 feet.

[@fet1612]

1:04 "What is airspeed?" "Airspeed is the speed of an aircraft relative to the air. An old adage says > You go too slow, you fall out of the sky. If your airplane goes too fast, you break up and you fall out of the sky. So there is a range of speed that can be your best friend when you are flying; typically when you are flying your coworker worked up, just go slow on the final approach, and you'll hear him speak like a parrot. He'll say, speed speed, speed speed, speed speed."

[@RealGoldRealWealth]

It seems that the speed tape by convention (and that is really my 'why' question) rolls higher IAS towards the TOP or higher than the datum. For a higher Altitude also higher than the datum. What is confusing to me is I see a higher Altitude towards the top and intuitively pitch up, but if I see a faster speed on the tape I need to pitch down, which to my mind is counter intuitive. Appreciate any help or explanation please.

[@subsonicflighttraining]

I think maybe your basing corrections on the speed and altitude displays. The attitude of the PFD and Thrust via the Thrust Levers are used to make corrections to maintain altitude and speed. Corrections are made with pitch and power based on what is required for speed and altitude. For example say you are at 9100 feet and you need to maintain 9000. A small Pitch change will be required while scanning V/S to return to 9000. Now let’s say your speed is increasing from 250 to 260. You need to squeeze off a little power to slow to 250 while continuing to scan your altitude to maintain 9000, then when the speed reaches 250, bump the power up slightly to maintain 250. Pitch and power are a dance, you change one, it affects the other. This is all assuming you have no FD’s on and the A/T is off. If they are on, FD’s give you commands for pitch and the A/T will maintain your speed. Understanding pitch/power relationships and a good scan are required when you start to maneuver like doing a visual approach to a landing. In the 747, it does not require a big pitch change to change your V/S by 500fpm, so small corrections are always the rule…

[@fet1612]

1:50 types of airspeed 1) IAS | Indicated AirSpeed 2) Calibrated AirSpeed 3) Equivalent AirSpeed 4) True AirSpeed ............................. 5) Ground Speed 6) Subsonic Speed 7) Supersonic Speed

[@michaeltaitt3083]

Can the GPS compute airspeed using time and distance info along with the reported wind speed? It seems that this would be safer than using pitot tubes

[@subsonicflighttraining]

GPS can compute ground speed like the 3 IRU's. Both the IRU's and GPS are very useful and accurate for FMS Based Calculations. GPS systems are not accurate as a real time instrument that pilots need because they cannot measure air and air density. So things like Mach number, stall speed, airspeed limits are obtained from Pitot Static Systems.There is some time latency with GPS as well and we need real time airspeed data when doing an instrument approach, not a speed that is several seconds lagging from transmitter to receiver. It is good in theory, but for the whole to work you need pitot static systems. We certainly use GS info in situations like Airspeed Unreliable where you can compare GS + - wind to come up with an airspeed in terms of comparison, but the real time nature of speed for all kinds of other calculations cannot be replaced.

[@michaeltaitt3083]

@@subsonicflighttraining thanks for the info. It makes sense if signals are being transmitted from satellites in space that there would be delays. Does the same apply to altitude? all these youtube videos show pilots working with pressure altimeters. Does VNAV get altitude from the GPS or from pressure?

[@subsonicflighttraining]

@@michaeltaitt3083 As far as I know, VNAV uses a Baro-VNAV Guidance system which is a combination of data from the pitot static system and the Air Data Computers...

[@RINKU23BRAVO]

Sir can flaps up speed overlap with vmvr min margin. Plz help me out sir

[@subsonicflighttraining]

I am not sure what vmvr is? Do you mean minimum maneuvering speed, the top of the yellow band on the Speed Display?

[@devillucifer8531]

Sir please make video on gyroscope

[@subsonicflighttraining]

Hi Moh, what is it you would like to see on the gyroscope, I assume you are talking about the IRS system...

[@mjmqubesi]

Hi Sir; When does "speed protection" become inactive??

[@subsonicflighttraining]

Anytime the Autothrottle is OFF or when you are in the Vertical Speed Mode, there is no speed protection...

[@mjmqubesi]

@@subsonicflighttraining VNAV: FLCH/ THRST: IDLE... (korean B 777 crash)

[@subsonicflighttraining]

@@mjmqubesi In VNAV you have speed protection via the elevator (pitch) when in VNAV SPD or via the A/T in SPD mode in VNAV PTH unless the A/T Arm Switch is Off, then you have no speed protection. In the case of FLCH, if you are in a descent using FLCH, there is speed protection via the elevator, FLCH SPD (pitch). If you were to intentionally or unintentionally not follow the FD in manual flight and raise the nose, speed would drop and the A/T would not correct because it is not controlling speed at this time, pitch is controlling speed. In the case of Korean, the pilot got slow because he started to pitch up in FLCH usage low to the ground. FLCH is not a mode that is intended to be used on approach, thus Boeing came out with a limitation not to use FLCH below 1000 feet...

[@mjmqubesi]

@@subsonicflighttraining We can say that A/T mode is speed at ( VNAV PTH - ALT - VNAV ALT) ... Here speed protected by A/T & Thrust mode at ( VNAV SPD - FLCH SPD - G/S ) & at these modes speed is protected by the elevators... isn't it?

[@subsonicflighttraining]

@@mjmqubesi Almost right on. Speed is protected by the A/T in VNAV PTH, VNAV ALT, and ALT. Speed is protected by Pitch through the elevator in VNAV SPD, FLCH SPD, and G/S. You do not have speed protection in V/S or in the FLARE mode. If you use V/S properly the A/T will maintain your speed as long as it can. But, if you call for a climb rate at +5000 fpm, eventually the A/T will go to the maximum reference thrust (for example full CLB) but the speed would continue to drop below what you are commanding and the jet can and will stall, there is no protection or can and will overspeed going the other way. In the flare mode during Autoland, the Thrust Levers go to Idle at 25 feet after the Flare mode started at 40 to 60 feet, depending on closure rate, and there is no speed protection for a short period there during the transition to touchdown using Autoland.

[@zalo_tuandriverga]

too complicated

[@subsonicflighttraining]

Yea, it is not for everyone, it is real training, some people don't care and just want to horse around with it as a game, and that is fine...