Aviation Rules of ThumbAviation Rules of Thumb

John Mahany, ATP/MCFIJohn Mahany, ATP/MCFIFlight Advisor, EAA Chapter 7Flight Advisor, EAA Chapter 7FAASTeam Lead Rep, KLGBFAASTeam Lead Rep, KLGBSeptember 13, 2011September 13, 2011

Checked Out From The SAFE Members Only Resource CenterSociety of Aviation and Flight Educators – www.safepilots.org 

ATA SmartBrief, 8/30/11ATA SmartBrief, 8/30/11

Automation prompts safety officials' concern about pilots' skills

Airplanes are become increasingly automated, leading some safety officials to raise concerns that pilots might be losing their in-flight instincts, which could be troublesome when faced with an issue. Rory Kay, co-chairman of the Federal Aviation Administration's committee on pilot training and an airline captain, says that the industry is suffering from "automation addiction," which is leading to different types of incidents.

ATA SmartBrief, cont.ATA SmartBrief, cont.

"We think the best way to handle this is through "We think the best way to handle this is through the policies and training of the airlines to ensure the policies and training of the airlines to ensure they stipulate that the pilots devote a fair amount they stipulate that the pilots devote a fair amount of time to manually flying," said Paul Railsback, of time to manually flying," said Paul Railsback, operations director at the Air Transport operations director at the Air Transport Association. "We want to encourage pilots to do Association. "We want to encourage pilots to do that and not rely 100% on the automation. I think that and not rely 100% on the automation. I think many airlines are moving in that directionmany airlines are moving in that direction." ."

More on piloting skillsMore on piloting skills

The ability of pilots to respond to the The ability of pilots to respond to the unexpected loss or malfunction of unexpected loss or malfunction of automated aircraft systems "is the big automated aircraft systems "is the big issue that we can no longer hide from in issue that we can no longer hide from in aviation," said Bill Voss, president of the aviation," said Bill Voss, president of the Flight Safety Foundation in Alexandria, Flight Safety Foundation in Alexandria, Va. "We've been very slow to recognize Va. "We've been very slow to recognize the consequence of it and deal with it."the consequence of it and deal with it."

Some Aviation Rules of ThumbSome Aviation Rules of Thumb

Navigation reciprocals Navigation reciprocals Normally aspirated & Turbo-chargedNormally aspirated & Turbo-charged Density AltitudeDensity Altitude Takeoff PerformanceTakeoff Performance Crosswind ComponentCrosswind Component Vx & VyVx & Vy Cruise ClimbCruise Climb

More Aviation Rules of ThumbMore Aviation Rules of Thumb

Flight Planning & ISAFlight Planning & ISA Figuring TASFiguring TAS Figuring VaFiguring Va Engine FailureEngine Failure Converting KTS to MPHConverting KTS to MPH Maximum GlideMaximum Glide Icing, weather, descent planning…Icing, weather, descent planning… Your own? Your own?

Navigation reciprocals Navigation reciprocals

Take the 1Take the 1stst digit plus two, 2 digit plus two, 2ndnd digit minus digit minus two; or visa versa; two; or visa versa; – Minus two, plus twoMinus two, plus two

180 becomes 360 180 becomes 360 090 becomes 270090 becomes 270

Related accident?Related accident?

Lexington, KY CRJ takeoff accident, Lexington, KY CRJ takeoff accident, – Aug. 27, 2006Aug. 27, 2006– Did they ‘brief’ the takeoff?? Did they ‘brief’ the takeoff?? – Were their ‘Heading Bugs’ properly set? Were their ‘Heading Bugs’ properly set? – They did not realize they were on the wrong They did not realize they were on the wrong

runway until it was too late, at rotation….runway until it was too late, at rotation….

Comair 5191 CVRComair 5191 CVR

Pilot: Thrust SetPilot: Thrust SetPilot: That is weird, No LightsPilot: That is weird, No LightsPilot: YeahPilot: YeahPilot: 100 KnotsPilot: 100 KnotsPilot: CheckPilot: CheckPilot: vee onePilot: vee onePilot: RotatePilot: RotatePilot: Whoa! Pilot: Whoa!

Generic Takeoff BriefingGeneric Takeoff Briefing

Departing KSNA or any other; confirm R/W _ _Departing KSNA or any other; confirm R/W _ _ If applicable, r/w is _ _ _ _ ft. longIf applicable, r/w is _ _ _ _ ft. long Density Altitude if applicable, is _ _ _ _ Density Altitude if applicable, is _ _ _ _ Takeoff weather/visibility is ‘X’; T/O alternate? Takeoff weather/visibility is ‘X’; T/O alternate? Up to Vr, will abort for _ _ _ Up to Vr, will abort for _ _ _ Once airborne, if engine fails then _ _ _ Once airborne, if engine fails then _ _ _ Any noise, DP or terrain issues?Any noise, DP or terrain issues? In event of emergency return, plan is ??In event of emergency return, plan is ??

Normally aspirated enginesNormally aspirated engines

A normally aspirated engine – only produces A normally aspirated engine – only produces rated Hp at Sea Level on a ‘Standard Day’, or rated Hp at Sea Level on a ‘Standard Day’, or ISA; 15C or 59F ISA; 15C or 59F

It loses 3 ½ % - 4% hp for each 1000’ increase It loses 3 ½ % - 4% hp for each 1000’ increase in altitude. in altitude.

Every 10 deg. F/6C above ISA results in 1% less Every 10 deg. F/6C above ISA results in 1% less power output power output

Turbo-Charged Engines Turbo-Charged Engines

Takeoff fuel flow –Takeoff fuel flow –– Your takeoff fuel flow should be at least 10%Your takeoff fuel flow should be at least 10%– of your max rated hp. ie., for 285hp, expect of your max rated hp. ie., for 285hp, expect – 28.5 gph; 310hp should be at least 31.0gph28.5 gph; 310hp should be at least 31.0gph– For turbo-normalized (8.5-1) it should be For turbo-normalized (8.5-1) it should be

somewhat lesssomewhat less– CHT during takeoff/climb should be < 380FCHT during takeoff/climb should be < 380F– Source, Mike Busch, Savvy AviatorSource, Mike Busch, Savvy Aviator

Density AltitudeDensity Altitude

For every 10F above ISA, add 600’ toFor every 10F above ISA, add 600’ to the airport elevation to figure density the airport elevation to figure density altitude and your airplanes performance. altitude and your airplanes performance.

source, Richard L. Collinssource, Richard L. Collins

Density Altitude Density Altitude

From AOPA Safety Advisor #6, From AOPA Safety Advisor #6, – Mastering Takeoffs and LandingsMastering Takeoffs and Landings– ‘‘the simple act of taking off or landingthe simple act of taking off or landing– accounts for 50% of all general aviationaccounts for 50% of all general aviation– related accidents’ related accidents’

Big Bear City, CA, takeoff - Big Bear City, CA, takeoff - 6748’ msl 6748’ msl

What is your density altitude?What is your density altitude? What is your takeoff performance?What is your takeoff performance? Do you know how to lean for takeoff?Do you know how to lean for takeoff?

– Begin the takeoff roll, and with full power, Begin the takeoff roll, and with full power, lean the mixture until there is some lean the mixture until there is some roughnesss, then enrichen until it runs roughnesss, then enrichen until it runs smoothly.smoothly.

– source, Mountain Flying Bible source, Mountain Flying Bible

Takeoff performance Takeoff performance

T/O distance increases 15% for each 1000’T/O distance increases 15% for each 1000’– Increase in Density Altitude above S.L. Increase in Density Altitude above S.L.

A 10% change in aircraft weight will result in a A 10% change in aircraft weight will result in a 20% change in the takeoff distance required20% change in the takeoff distance required

source; Mountain Flying Biblesource; Mountain Flying Bible

Takeoff flap settingTakeoff flap setting

If you want to use flaps for takeoff, but If you want to use flaps for takeoff, but there is no reference in the P.O.H., suggest there is no reference in the P.O.H., suggest turning the yoke full scale, either direction turning the yoke full scale, either direction and lower the flaps to approximately and lower the flaps to approximately match the down aileron deflection.match the down aileron deflection.

source, Mountain Flying Bible source, Mountain Flying Bible

Takeoff performanceTakeoff performance

Short field takeoff advice from the late Sparky Short field takeoff advice from the late Sparky Imeson, noted mountain flying expert; Imeson, noted mountain flying expert;

If you have not reached 70% of your takeoff If you have not reached 70% of your takeoff speed ½ way down the runway, ABORT! speed ½ way down the runway, ABORT!

Also, make sure the parking brake is OFF! Also, make sure the parking brake is OFF!

source, Mountain Flying Biblesource, Mountain Flying Bible

Crosswind componentCrosswind component

The 5, 7, 9 ruleThe 5, 7, 9 rule– Runway numbers are magnetic; ATIS/ASOS Runway numbers are magnetic; ATIS/ASOS

winds are magneticwinds are magnetic– If the wind is 30, 45 or 60 degrees to the R/WIf the wind is 30, 45 or 60 degrees to the R/W

Take 50, 70 or 90% of the wind velocity; this Take 50, 70 or 90% of the wind velocity; this becomes the direct crosswind component.becomes the direct crosswind component.

Note; Crosswinds Note; Crosswinds are not hard limits; they are ; they are only ‘demonstrated’; more importantly, how is only ‘demonstrated’; more importantly, how is your cross-wind proficiency? your cross-wind proficiency?

Vx & VyVx & Vy

Both Vx & Vy decrease 1 knot per Both Vx & Vy decrease 1 knot per 100 pounds below max gross weight100 pounds below max gross weight Verify this in the P.O.H.Verify this in the P.O.H.

Cruise Climb speed Cruise Climb speed

Vy – Vx = C. Add C to Vy, this is cruise climbVy – Vx = C. Add C to Vy, this is cruise climb Ex., a CE 172S; Vy 74 knots; Vx 62; C = 12Ex., a CE 172S; Vy 74 knots; Vx 62; C = 12 74 + 12 = 86 74 + 12 = 86 suggestedsuggested for cruise climb. for cruise climb. P.O.H. shows 70 – 85Kts for cruise climbP.O.H. shows 70 – 85Kts for cruise climb

A more efficient climb. Better engine cooling A more efficient climb. Better engine cooling with a lower, better deck angle. Source, with a lower, better deck angle. Source, FlyFly

the Enginethe Engine, Kas Thomas , Kas Thomas

Flt. Planning - Figuring ISAFlt. Planning - Figuring ISA

Int’l Standard Atmosphere…ISA Int’l Standard Atmosphere…ISA Found in the P.O.H. in performance chartsFound in the P.O.H. in performance charts

– ISA is 59F or 15C at sea level, 29.92”hgISA is 59F or 15C at sea level, 29.92”hg– To find ISA at altitude; take cruise altitude, x 2, To find ISA at altitude; take cruise altitude, x 2,

subtract 15, then change the sign (+/-) subtract 15, then change the sign (+/-)

– 5,000’; 5 x 2 = 10 - 15 = -5; becomes +5. 5,000’; 5 x 2 = 10 - 15 = -5; becomes +5. – 10,000’; 10 x 2 = 20 – 15 = +5; becomes -510,000’; 10 x 2 = 20 – 15 = +5; becomes -5

Figuring TASFiguring TAS

How to find your approximate TASHow to find your approximate TAS– TAS increases approximately 2% per 1000’TAS increases approximately 2% per 1000’– What is your indicated altitude?What is your indicated altitude?– Double the 1Double the 1stst digit, and add to the IAS. digit, and add to the IAS.– Result should approximate TASResult should approximate TAS– Example; 3000’, and 120 knots, TAS is ~ 3 x Example; 3000’, and 120 knots, TAS is ~ 3 x

2 = 6, 120 + 6 = 126 knots2 = 6, 120 + 6 = 126 knots

The ‘ice tea’ airspeed formulaThe ‘ice tea’ airspeed formula

Airspeed relationships; how to remember Airspeed relationships; how to remember The ‘iceT’ formula; indicated ~ calibrated, The ‘iceT’ formula; indicated ~ calibrated,

equivalent (applies to jets), True Airspeed. equivalent (applies to jets), True Airspeed. TAS increases with altitude. Indicated will TAS increases with altitude. Indicated will decrease with altitude due to less dynamic decrease with altitude due to less dynamic pressure in the Pitot tube pressure in the Pitot tube

Rule of 60 Rule of 60

At cruise TAS, each degree of crab angle At cruise TAS, each degree of crab angle x TAS multiple (60=1, 120=2, etc)x TAS multiple (60=1, 120=2, etc) = crosswind component= crosswind component Ie., @ 120 knots, each degree of crab is Ie., @ 120 knots, each degree of crab is

caused by a 2 degree x-wind component caused by a 2 degree x-wind component resulting in a ‘x’ degree drift correction. resulting in a ‘x’ degree drift correction.

Ex., 5 degrees left x 2 = 10 knot cross Ex., 5 degrees left x 2 = 10 knot cross windwind

Maneuvering Speed VaManeuvering Speed Va

Maneuvering Speed; Va = ~ 1.7 x Vs1Maneuvering Speed; Va = ~ 1.7 x Vs1

Reduce Va by 10% for each 20% reduction in gross Reduce Va by 10% for each 20% reduction in gross weight. Or, reduce by 1% for each 2% reduction in G.W. weight. Or, reduce by 1% for each 2% reduction in G.W.

Remember, you are always BELOW G.W. at cruise. You Remember, you are always BELOW G.W. at cruise. You burned fuel on taxi, takeoff and climb. burned fuel on taxi, takeoff and climb.

All ‘V’ speeds are predicated on G.W., so adjust All ‘V’ speeds are predicated on G.W., so adjust accordingly for best performance. accordingly for best performance.

Engine failure A, B, C’sEngine failure A, B, C’s

AirspeedAirspeed – best glide – best glide

Best placeBest place to land – straight ahead, to the to land – straight ahead, to the side, or behind you?side, or behind you?

AircraftAircraft Control – maintain control! – maintain control!– Know your emergency checklistKnow your emergency checklist! !

Engine Failure, Maximum Engine Failure, Maximum GlideGlide

Weight has Weight has nono effect on max effect on max glide range Weight Weight doesdoes have an effect on glide have an effect on glide speedspeed Reduce glide speed 5% for each 10% Reduce glide speed 5% for each 10%

reduction in gross weightreduction in gross weight With a headwind, increase glide speed by With a headwind, increase glide speed by

50% of the headwind component. Glider 50% of the headwind component. Glider pilots use this technique. pilots use this technique.

Converting KTS to MPHConverting KTS to MPH

Add 15%, or multiply by 1.15Add 15%, or multiply by 1.15

100kts = 115mph100kts = 115mph

IcingIcing

No aircraft is certified for CONTINUOUS No aircraft is certified for CONTINUOUS flight in KNOWN icing conditionsflight in KNOWN icing conditions

Icing/deice certification is only for flight Icing/deice certification is only for flight THROUGH icing. Ref. FAR 25 Appendix THROUGH icing. Ref. FAR 25 Appendix C, icing certificationC, icing certification

Check your P.O.H.Check your P.O.H. From, Professional Pilot, 3From, Professional Pilot, 3rdrd. ed., John . ed., John

Lowery Lowery

Weather…Weather…

A rough rule of thumb for avoiding/escaping A rough rule of thumb for avoiding/escaping icing conditions – but it varies each timeicing conditions – but it varies each time– Climb in a cold front towards colder temps (away Climb in a cold front towards colder temps (away

from ice); if temps in the bases of developing from ice); if temps in the bases of developing cumulus clouds is -12C or warmer…expect heavy cumulus clouds is -12C or warmer…expect heavy icingicing

– Descend in a warm front to warmer temps belowDescend in a warm front to warmer temps below– Sources, Sources, Severe Weather FlyingSevere Weather Flying, Dennis Newton, Dennis Newton– Weather FlyingWeather Flying, Bob Buck, Bob Buck

Weather/TRW rules…Weather/TRW rules…

Storms tend to be stronger when the cold Storms tend to be stronger when the cold frontal passage occurs in the afternoon or frontal passage occurs in the afternoon or evening. This is because the air can get evening. This is because the air can get more more unstable out ahead of the front (i.e. daytime heating).

IFR Standard Rate Turn bank IFR Standard Rate Turn bank angleangle

Take 10% of the IAS and add 5. Take 10% of the IAS and add 5.

Ground SpeedGround Speed

Rough estimate Rough estimate

– Add or subtract all of the headwind or Add or subtract all of the headwind or tailwindtailwind

– Add or subtract ½ of a quartering head or Add or subtract ½ of a quartering head or tailwindtailwind

Calculating Ground Speed - Calculating Ground Speed - piston driverspiston drivers

Note the time to fly a distance; ie., 30NM Note the time to fly a distance; ie., 30NM 30/15; 15x 4 = 60; 4 x 30 = 12030/15; 15x 4 = 60; 4 x 30 = 120

– 15 min to fly 30NM. G.S. = 120kts. 15 min to fly 30NM. G.S. = 120kts. 10 min to fly 25NM; 10x6=60; 6x25 = 150 kts10 min to fly 25NM; 10x6=60; 6x25 = 150 kts

Ground Speed Check - Ground Speed Check - VLJ driversVLJ drivers

For faster aircraft (at least 250 kts.) there For faster aircraft (at least 250 kts.) there is another G.S. checkis another G.S. check

Note the distance travelled in 36 seconds Note the distance travelled in 36 seconds on the DME and multiply by 100. on the DME and multiply by 100.

36 seconds is 1% of an hour. 36 seconds is 1% of an hour. So, if you travel 3NM, ground speed is So, if you travel 3NM, ground speed is

300 kts. 300 kts.

How to plan descentsHow to plan descents

Suggestion; altitude to lose times 2 (500 Suggestion; altitude to lose times 2 (500 FPM for pax comfort), times ground speed FPM for pax comfort), times ground speed in miles per minute (1,2, 3, etc.), this is in miles per minute (1,2, 3, etc.), this is how many miles you will cover how many miles you will cover descending…adjust as needed for wind descending…adjust as needed for wind and plan when to start down accordingly and plan when to start down accordingly

Descent planning from the Descent planning from the flight levelsflight levels

Multiply cruise altitude ( thousands of Multiply cruise altitude ( thousands of feet) x approx. 3 (depending on the feet) x approx. 3 (depending on the aircraft and winds) to determine the aircraft and winds) to determine the approximate start of descent. approximate start of descent.

To descend from FL 250; 25 x 3 = 75To descend from FL 250; 25 x 3 = 75 Begin descent 75 NM out Begin descent 75 NM out

Intercept the glideslopeIntercept the glideslope

At G.S. intercept, lower the nose exactly At G.S. intercept, lower the nose exactly whatever the G/S angle is, as shown on the whatever the G/S angle is, as shown on the approach plate. Capture is automatic. approach plate. Capture is automatic.

This is typically ~ 3 degrees. This is typically ~ 3 degrees. source, Barry Schiff, Proficient Pilotsource, Barry Schiff, Proficient Pilot

Flying the glideslopeFlying the glideslope

Determine the proper ILS descent rate Determine the proper ILS descent rate – Standard ILS descent rate = 300’/NM. Standard ILS descent rate = 300’/NM. – Take IAS / 2, add a zero; this is your Rate of Take IAS / 2, add a zero; this is your Rate of

Descent; 100kts / 2 = 50, add a ‘0’ = 500 Descent; 100kts / 2 = 50, add a ‘0’ = 500 FPM. 120 kts = 600 FPMFPM. 120 kts = 600 FPM

Or, use this to figure the altitude to be at a given Or, use this to figure the altitude to be at a given distance from a runway…for a stabilizeddistance from a runway…for a stabilized

approachapproach

Landing…Landing…

Approx. 42% of G.A. accidents occur Approx. 42% of G.A. accidents occur during approach and landingduring approach and landing– If the runway is wet and ungrooved, the If the runway is wet and ungrooved, the

landing ground roll doubleslanding ground roll doubles– Crossing the runway threshold higher than 50 Crossing the runway threshold higher than 50

feet; landing distance increases ~ 200’ for feet; landing distance increases ~ 200’ for every 10’ of excess heightevery 10’ of excess height

– Every 10 kts of excess speed increases Every 10 kts of excess speed increases landing distance 20%landing distance 20%

Misc…Misc…

For each 1000’ above S.L., the takeoff run For each 1000’ above S.L., the takeoff run will increase ~ 12%will increase ~ 12%

Others…Others…

Rollout from a turn; lead your bank by ½ Rollout from a turn; lead your bank by ½ the bank anglethe bank angle

Most structural icing occurs between 0C - Most structural icing occurs between 0C - 10C 10C

Your ownYour own

Rules of Thumb???Rules of Thumb???

Thank you! Thank you!

j.mahany@charter.net www.johnmahany.com

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