killer in aviation 1 in 60 rule

7/27/2019 Killer in Aviation 1 in 60 Rule

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NON PRECISION APPROACH

Major Killer In Aviation

Facts: 1984 – 1996 (From FSF)

• More than 30 CFIT crashes involving large jetliners• Over 65% were non-precision approaches (VOR)

• 80% of them were flown by the captains involved

• Co-pilots involved not assertive enough?

VOR Approaches Are 5 Times More Deadly Than ILS



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Killer In Aviation –FSF Report

A Study Based On 287 CFIT Crashes Of All Categories Of Airplanes



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Boeing Accident Statistics

1992-2001



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Some Infamous CFITs While

Executing Non-Precision Approaches

1. Flying Tigers B747-200 Freighter Flt 66 In KL (18.2 1989)

2. Air Inter A320 Flt 148 In Strasbourg (20.1.1992)

3. PIA A300 Flt PK 268 In Kathmandu (28.9.1992)

4. AA B757 Flt 965 In CALI (20.12.1995)5. USAF CT-43A (B737) In Dubrovnik – Croatia (03.04.1996)

6. Korean Air B747-300 Flt 801 In Guam (7.8.1997)

7. Thai Airways A310 Flt 261 In Surat Thani (11.12.1998)

8. Gulf Air A320 Flt GF072 In Bahrain (23.8.2000)

9. CrossAir Avro RJ100 Flight 3597 In Zurich (24.11.2001)

10. And More! Many more!



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Pilots Were Unfamiliar With The Mechanics Of Non-

Precision Approaches That Killed Them



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Using 1 in 60 Rule To Determine:

Descent Gradient

Climb Gradient

Descent Angle Climb Angle

Rate Of Descent

Rate Of Climb Crosswind Correction



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1 in 60 Rule

One part vertical distance = 60 parts of horizontal distance

For every 60ft, 1° angle will subtend a height of 1 foot

For every 6000ft, 1° angle will subtend a height of 100 feet For every 1nm, 1° angle will subtend a height of 100 feet

For every 1nm, 3° angle will subtend a height of 300 feet

Note: 1 nm = Approximately 6000 feet



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A Typical 3° ILS Slope

On a typical 3° ILS slope

If FAF is at 10nm (♎ 60000ft),

It will be about 3000ft in altitude.

Note: 1 nm = 6076 feet



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Express In Gradient (%)

Gradient = Vertical distance ÷ Horizontal distance

Gradient % = (Vertical distance ÷ Horizontal distance) x 1003000/60000 = 1/20 or 0.05 = 5% (0.05 x 100)

300/6000 = 1/20 or 0.05 = 5%

Commit To Memory! 1nm = 300ft



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Gradient & Slope Relationship

Gradient = Vertical Distance / Horizontal Distance Gradient (%) x 0.6 = Slope Angle

5.0% Gradient x 0.6 = 3°

Or 3° ÷

0.6 = 5.0% Gradient!Example: 11% gradient x 0.6 = 6.6°

(Kathmandu VOR-DME Rwy 02)

To Be precise (Using Trigonometry):

• 5.0% Gradient Is Actually = 2.9 °

• 3° = 5.24% Gradient

• 1° Subtends A Ratio Of Exactly 1 : 57.3



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Gradient & Groundspeed

Relationship

Gradient x Groundspeed = ROC or ROD

• 5% minimum climb gradient x 180kt = 900fpm r.o.c.

• 5% descent gradient (3° slope) x 150kt = 750fpm r.o.d.

Some Examples:



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To Prove That Gradient x

Groundspeed = ROC/ROD

The B744 has a typical heavyweight V2 speed of 180kt.

If the SID requires a minimum climb gradient of 5%.

(e.g. on Changi rwy 02L to clear the ship mast at 1km from end of rwy.)

What is the minimum ROC required to achieve that?



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Jeppesen Conversion Nomogram



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CAUTION!

Do Not Mix Up Gradient With Slope Angle

It Is Potentially Fatal To Regard 5° Slope As

5% Gradient.

Or To Regard 3° Slope As 3000fpm Rate Of

Descent



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Crosswind Correction

Using 1 In 60 Rule

The approach speed is 150kt, ground track is 270º, a crosswind from the right of 10kt,

What is your heading to make good the track (drift angle)?

Answer: 4º



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Using Trigonometry To

Calculate Gradient & Angle

Tangent θ (gradient) = Vertical Distance / Horizontal Distance

Gradient (%) = Vertical Distance x 100 or Tangent θ x 100

Horizontal Distanceθ = Gradient (%) (where θ is the slope angle)

Tangent x 100

e.g. 6.5% Gradient = 0.065/Tangent = 3.7º

Approach Chart Designers Use This Method

For Accuracy Purpose

(You Need A Scientific Calculator)



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Slant Range & Ground Distance

When The Angle Is Small (3º-6º),

Tangent & Sine Value Are Quite Similar.

5.24% Gradient = 0.0524 x Tan-1 = 3º (Ground Dist – FMS)

5.24% Gradient = 0.0524 x Sine-1= 3º (Slant Range – DME)



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1 In 60 Rule Is Safe To Use

It is safe to use the 1 in 60 rule to figure out your

descent angle or path of a non-precision approach

(VOR-DME, VOR only, or NDB/LOCATOR approach),

as long as there are no obstacles along the descentpath, you can execute a continuous descent profile

(Constant angle non-precision approach – CANPA).

However, if obstacles exist, you have to observe the

prescribed safety heights to avoid terrain contact!

Tips: Study The Destination’s & The Emergency

Alternates’ Non-Precision Approach Charts While

In Cruise Phase, Figure Out The Gradient,

Descent Angle & Groundspeed. The Early You

Prepare, The Less Likely You Will Get Caught.



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Test Your New Skill

NZ Christchurch VOR-DME Rwy 20



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Kerman VOR-DME Rwy 16



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If You Are Asked To Do A Charter Flight To

Kathmandu In Short Notice, Are You Ready

For It?

Kathmandu VOR Rwy 02

From D10 to D5.0 (6076ft x 5 = 30380ft)

9500ft – 6100ft = 3400ft

Sine ɵ = 3400/30380 = 0.1119 = 11.2 % gradientɵ = 6.4º

At ISA + 15º : 160Kt IAS = 192Kt TAS

Rate Of Descent = 11.2 x 192 = 2150fpm



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WSSS’ ANITO 3B SID



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Hong Kong ILS-DME RWY07L

What Is The Rate Of Climb Required? –

Approach Speed 160kt, Nil-wind Condition and OAT 15º



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The Elegance 1 In 60 Rule

It Seamlessly Tackles SPEED, ALTITUDE &DISTANCE In The World Of Aviation

It Has Beauty & Elegance

It Is Practical & Easy To Use

It Works Well With GA Airplanes All The WayTo Commercial Jetliners

It Is A Good Back-Up Skill When All The“Goodies” Failed To Work

It Only Breaks Down When The Angle GetsToo Large



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The EndThis Has Been A Technical Presentation By Capt Eddie Foo S N.

The “1 In 60 Rule” Paper Was Published In

The SIA Flight Safety Magazine – IssueNo 89 – Dec 2003.

For A Personal Copy Of The

“1 In 60 Rule” Paper, just e-mail to me

[email protected]

killer in aviation 1 in 60 rule

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