Questions tagged [airspeed]

The speed of an aircraft relative to the air. Among the common conventions for qualifying airspeed are: indicated airspeed ("IAS"), calibrated airspeed ("CAS"), true airspeed ("TAS"), equivalent airspeed ("EAS") and density airspeed.

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8
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2answers
5k views

How is the airspeed-Mach number transition handled in modern airliners?

During the climb phase, how is the transition from constant speed (IAS) to constant Mach number handled? Does the pilot flying have to manually "push the button" on the control panel, or is the ...
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1answer
232 views

At which speed is a plane traveling at hypersonic? [duplicate]

What is the measurement used when a plane is said to travel at hypersonic? How does the air act at the nose of the plane? Would the nose and wing have to be razor sharp to cut the air? because the ...
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5answers
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What will the pilot do if all the airspeed indicators fail?

Are there any alternate instruments to indicate the airspeed in case of pitot tube failures?
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956 views

Is it possible to fly a Straight and Level flight at high speed?

The question arise while discussing with some of my student pilot friends that as we have been performing Slow Flight we have to keep increasing the AOA of the aircraft to compensate for every lose in ...
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1answer
260 views

How does supercruise thrust compare with static thrust ASL?

As I understand it, turbojet thrust decreases both with altitude due to rarefied air reducing massflow, and airspeed due to a smaller speed increase between intake and exhaust relative to the airframe....
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2answers
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Why do Vx and Vy coalesce at an airplane's absolute ceiling?

I'm struggling to figure out why that is the case. I'm trying to determine why the best angle of climb speed equals to best rate of climb speed at the absolute ceiling on airplanes.
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What alternatives to pitot static systems are available or in development?

Air France 447 is a powerful example of what a serious situation unreliable air data indications can be if not handled properly by a crew. Still, whether crews are properly trained or use that ...
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3answers
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What if an airspeed prescribed by a published procedure isn't safe for a particular aircraft's operations?

Departure and arrival procedures often prescribe airspeeds which must be maintained at certain fixes. 14 CFR 91.117 sets rules for airspeeds but has a paragraph which states that the airspeeds don't ...
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What aircraft fly faster than 250 knots indicated airspeed under 10,000 feet for safety reasons?

14 CFR 91.117 limits aircraft to 250 knots indicated airspeed below 10,000 feet, but 91.117(d) allows aircraft to fly a higher speed if the minimum safe speed is higher. What aircraft and aircraft ...
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How do head- and tailwinds affect airspeed?

I'm sure this was asked somewhere, I just can't find it. So if it's a dupe, let me know. Anyway, I'm one of those guys that actually looks at the flight information when I'm flying. I fly ...
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1answer
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Do Air Traffic Controllers have to remember stall speeds for different aircraft?

While dealing with Takeoffs and Landings controllers provide speeds to pilots for different phases of the flight, specially during a landing approach. How do they know which speeds are safe for all ...
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How does a Machmeter behave if the static port is blocked during a constant CAS climb?

Question: How will the machmeter behave in a constant CAS climb if the static source becomes blocked? Answer: The machmeter reading will decrease. Why? I couldn't find any logical reason for the ...
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0answers
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In an Inertial Measurement Unit, how are the body-axis velocities calculated?

What are body-axis velocity components (u,v,w)? Are they calculated from IMU acceleration components (Ax,Ay,Az)? How can this be related with the airspeed measured from the pitot tube?
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How do pilots manage the speed during the approach?

Once the initial approach fix is reached, what are the different "speed stages" to the runway? I often read about landing speed and approach speed. For example on this chart, Boeing indicates ...
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1answer
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How does headwind influence the results of a pitot tube and therefore the airspeed indicator?

What I know so far I recently read about pitot tubes and their use in aircraft. For the basics I consulted Wikipedia, and also went through the definitions for airspeed, groundspeed, and the various ...
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4answers
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When does the overspeed alarm goes off in a plane?

I want to know when does the overspeed goes off in aircraft. How exactly is overspeed limit decided? Is it fixed for all the situations, or does it keeps changing? In a game that I play, (Infinite ...
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1answer
612 views

Is airframe heating a concern at subsonic speeds?

It is a well-established fact that airframe and skin heating due to air friction is a significant concern with supersonic aircraft. However, below Mach 1 (i.e. typical commercial aircraft flights ...
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3answers
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What are CAS and EAS used for?

What are calibrated airspeed (CAS) and equivalent airspeed (EAS) used for? When would a pilot need to know these?
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4answers
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If planes can go faster, why don't airlines fly faster? [duplicate]

I came across this page where a DC-8 set a record in 1964 for a 12h24m flight from Montreal to Tokyo. Last year I flew to Tokyo from Montreal and it took 9h from Vancouver (where I had a layover) I ...
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1answer
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How is TAS affected by wind?

Does True Air Speed (TAS) change with wind speed and direction? My understanding is that if an aircraft were travelling at 470kt TAS, with a hundred knot tailwind, the ground speed would be 570kt. In ...
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1answer
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How to get from IAS in MPH to KCAS using POH graph of best TAS/GPH?

My understanding is that in order to find the V(L/D)max I can do the following steps: Look in the Pilot's Operating Handbook (POH) and find the performance reflecting the best TAS/fuel flow. Find the ...
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Why must Vr be set so precisely?

Why must VR (Rotation Speed) be set so precisely? I mean why can't they just say: Rotate the Aircraft at 120 to 150 knots And then, the pilot thinks: OK, I have a full plane and half full tanks,...
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Why does the speed of commercial airliners fluctuate, sometimes as high as 1,060 km/h or as low as 800 km/h?

I've noticed that (long-haul) airliners sometimes travel at as high as 1000 km/h (I believe I've even seen 1040 km/h), but usually they fly closer to 800 km/h, for most of the trip. This seems odd ...
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How does experienced pressure vary with airspeed?

Drag increases with the square of airspeed. Is the same true of the pressure that a forward-facing area experiences? As an aircraft approaches and then exceeds the speed of sound, how does ...
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How does the IAS stall speed vary with increasing altitude?

First of all, we all know what IAS is and if not for some people you can follow this link to read the basics about stall and the differents speeds. So we also know that our TAS/ Mach number will ...
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When to slow down to Va for turbulence?

I'm trying to figure out when it is safe to continue at normal cruise speed and when I should slow down to avoid over-stressing the airframe due to turbulence. (of course I have asked instructors but ...
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Is trimming for constant speed equal to trimming for constant angle of attack?

My understanding of trim: When you say you have trimmed an aircraft for a constant speed, say 100 mph, you are actually trimming the horizontal stabilizer so that there are no forces on stick (or tail ...
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3answers
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Can a helicopter really fly with rotors going this slow?

I was watching this youtube video and I noticed that at 3:17 seconds they show a coast guard helicopter rescuing a man from a ship. Whats shocking about this is that the main rotor of the helicopter ...
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What is the relation between airspeed and rate of turn?

I am reading about aircraft maneuvering and the end of section check contains this question: During a turn, if you reduce the airspeed and maintain the angle of bank, the result is a _____________ ...
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4answers
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Knots vs MPH, is there some standard for when to use which unit?

In looking at all the sources of aviation data, including POH's, instrument dials, instructional materials, FAA publications, METAR's, flying magazine stories, YouTube videos, etc., I see no standard ...
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What is the reference used when measuring flight speed?

I'm a physicist who was amused by the argument in the comments of this question about gravity. The correct answer about the affect of the accelerating reference frame of the plane on the apparent ...
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451 views

SR-72 — is the speed reported in this story wrong?

I was just reading this story from Sky news and reported the following Lockheed Martin says it is close to developing a military plane that flies at Mach 6 - six times the speed of sound, which ...
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8answers
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What happens if you exceed the maximum speed on a C172?

The airspeed indicator has a red marking that means: "never exceed this speed" ($V_{NE}$, around 160 KIAS). Why can't you exceed that speed?
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1answer
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What is the difference between ground speed and airspeed? [duplicate]

What is difference between ground speed and airspeed? Is ground speed used only for takeoff or is it used for flight too?
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How do you convert true airspeed to indicated airspeed?

Is this something found in the POH? I know there is a IAS and CAS chart.
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1answer
6k views

How do you calculate indicated airspeed on a flight plan?

I'm planning my cross country journey for my flight test and it seems I forgot how to calculate my indicated airspeed. The indicated airspeed must be from the POH, right? The the true airspeed is ...
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1answer
534 views

What is the effect of earth's speed on flight? [duplicate]

What happens if an object (plane or space ship) travels at a speed less than that of earth rotation?
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1answer
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What is the correct crew procedure for an unreliable airspeed alert?

When the crew receives "airspeed disagree" message on the primary flight displays, they may face some hazardous situation. Is there any procedure, using a table containing pitch, power, altitude and ...
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4answers
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Which air stream pressure / speed is measured by the pitot?

The pitot tube is used to measure the air pressure later converted into air speed. However air pressure varies according to several elements, including the location related to the wing: (Source: av8n....
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2answers
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What is “airspace underlying a Class B airspace area designated for an airport”?

For the purposes of airspeed restrictions within airspace, the FAA regulations list the following area description (emphasis mine): 14 CFR 91.117 (C) No person may operate an aircraft in the ...
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1answer
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How do I calculate aircraft range with these parameters?

The parameters are: MTOW, MLW, MZFW, OEW, maximum fuel weight, fuel flow rate and true airspeed. Measured in lbs and kts. Not given drag so unsure how to apply Breguet equation. Trying to construct a ...
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2answers
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Are there technical means to enforce aircraft speed limits as well as regulatory means?

Do any aircraft have a device which can be pre-set or can be controlled from the ground in order to prevent the aircraft from exceeding a speed limit? These could be similar to what they have for ...
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3answers
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How to determine aircraft altitude and speed, as a passenger?

Is it possible for a passenger to determine the aircraft's altitude and or speed or location using any mobile apps. Not all airlines have displays with constant info about this. I had tried using ...
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1answer
3k views

Is it possible to modify an AV-8B Harrier II to a supersonic aircraft by applying some modification?

Is it possible to convert McDonnell Douglas/BAe Systems AV-8B Harrier II Plus into an effective and usable supersonic aircraft? May be, by changing the engine or applying some modifications on the ...
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1answer
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Why are speed restrictions imposed for flights flying below 10,000 ft?

I know that restrictions do not always apply and ATC can cancel them or pilots can request for speed restriction being canceled. But why is there such a speed restriction in first place? Are there any ...
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4answers
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What's the minimum cruise speed of modern airliners?

Often when approaching landing, I feel the aircraft slow down considerably, it hasn't landed yet, but kind of hovers around waiting for clearance to land. Thus I was wondering, is there any defined ...
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2answers
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Is there a maximum airspeed to deploy a ram air turbine?

Is there any airspeed limit for deploying a ram air turbine? Can airspeed be determined from the rate of its propeller rotation? Could that data be used to determine altitude?
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3answers
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What is the relation between airspeed and altitude at fixed throttle setting in a private jet?

In the world of private jets, say a G-450, at a fixed throttle setting, does it simply go faster the higher it climbs/flies?
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2answers
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Is it quiet in the cockpit when flying faster than the speed of sound?

Is it quiet in the cockpit when flying faster than the speed of sound or is the noise from air resistance just too loud? Similar question: is it quieter at the front of an airliner flying faster ...
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7answers
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What is the fastest possible transatlantic flight today?

I'm working on a novel that, as part of the backstory, requires samples of a biological agent to be flown from Incirlik Air Base to labs across Europe, and then finally from the UK to the US. In the ...