Night VFR

Introduction

Aims

  • To understand the principles of Night VFR flight

Objectives

  • At the end of this lesson, the student will be able to:
    • Understand the illusions that might affect a pilot flying at night
    • Explain what PAL is and how it works
    • Understand the privileges of a NVFR rating

The Night VFR Rating

  • Allows you to pilot an aircraft at night under the VFR, after last light or before first light
  • It is not an IFR rating
  • You must still be able to operate in visual conditions — although it is a good introduction to flying on instruments
  • The rating is meant to allow flexibility — to land after last light if your departure was delayed, for example

The Night VFR Rating

  • Per CASR1998 61.975 and CASR1998 61.980, to be issued an NVFR rating, you must have, in addition to a current PPL(A) or higher:
    • At least 10 hours aeronautical experience in an aeroplane at night
    • At least 5 hours dual cross country flight time at night
    • Two dual cross country flights at night, each with:
      • at least one landing at an aerodrome, other than the aerodrome from which the flight began
      • the aerodrome is remote from extensive ground lighting
    • At least 1 hour of solo circuits at night
    • At least 3 hours dual instrument time

The Night VFR Rating

  • As a Day VFR only pilot, you must plan to be on the ground 10 minutes before last light, per AIP ENR 1.2
  • The Night VFR rating, obviously, removes this restriction
  • Remember it is not an instrument rating

VFR Minima Refresher

Airspace/Altitude Flight Visibility Horizontal distance from cloud Vertical distance from cloud
A VFR flight not permitted VFR flight not permitted VFR flight not permitted
C (below 10000ft AMSL) 5000 metres 600 metres 1000ft
D 5000 metres 600 metres 1000ft above, 500ft below
E (below 10000ft AMSL) 5000 metres 1500 metres 1000ft
G (above 1000ft AGL or 3000ft AMSL) 5000 metres 1500 metres 1000ft
G (below 1000ft AGL or 3000ft AMSL) 5000 metres clear of cloud, in sight of surface clear of cloud, in sight of surface

Sunset versus Last Light

Aircraft cockpit at last light

  • The words sunset and sunrise have no relevance to a VFR pilot
  • It can be after sunset but still adequate light outside to make an approach and landing
  • Last light is where the sun is beyond 6° below the horizon
  • First light is where the sun is 6° below the horizon and rising

Calculating Last Light

Aircraft cockpit at last light

  • Can use AIP GEN 2.7 — Sunset and Sunrise Tables
  • Or NAIPS/OzRunways/Foreflight, etc
  • Far easier these days than it used to be

Instruments for NVFR Flight

CAO 20.18, Appendix IV
  • Airspeed indicator
  • Pressure altimeter
  • Magnetic Compass
  • Panel clock or wristwatch
  • OAT indicator
  • Attitude Indicator
  • Heading Indicator
  • Turn coordinator
  • Suction gauge

Suction Gauge

Vacuum Gauge

  • This gauge tells the pilot that the vacuum system is functioning correctly
  • If the vacuum system dies, you will lose your attitude indicator and directional gyro
  • Check the suction gauge with every instrument scan
  • It is normal for the gauge to fluctuate at idle because the vacuum pump is engine driven
  • If the gauge registers a decline in cruise flight, declare an emergency

Aerodrome Lighting

Aerodrome Lighting

Why?

  • Obviously we need to be able to see where we’re taxiing or else we’ll hit another aeroplane!
  • Aerodromes can have different types of lighting
    • Major international airports can have apron lighting, taxiway lighting and runway lighting
    • Other smaller airfields (such as Redcliffe) only have an illuminated runway

Taxi Lights

Taxi Lights

  • Edge lights are Blue
  • Centreline lights are Green

Runway Lights

Runway Lights

  • Threshold lights are Green
  • Edge/Centreline lights are White
  • End of Runway lights are Red

Other Lights

  • The windsock is illuminated at night — important for pilot activated lighting too
  • The terminal area is illuminated at some airports (including Archerfield)

PAPI

PAPI

  • Larger airports have what’s called a PAPI — Precision Approach Path Indicator
  • Two or four lights on the side of the runway
  • Lights change if you’re too high or low
  • Red on white, you’ll be alright
    • If the lights are all red, you’re too low
    • If the lights are all white, you’re too high

Pilot Activated Lighting (PAL)

ERSA Aerodrome Lighting

  • Allows pilots to turn on the lighting when required rather than wasting money by keeping lights on all the time
  • Controlled by a series of radio clicks within a specified timeframe
  • Noted in ERSA/AIP

Using PAL

  • Once you activate PAL, the lights will stay on for 30 minutes
  • At airports with an AFRU, you will be told when there are 10 minutes remaining before the lights go off
  • The windsock will also flash
  • Simply key the microphone three times and the lights will remain on for another 30 minutes

Aeroplane Lighting Requirements

Aircraft Cockpit Lighting

CAO 20.18 Appendix V

Aircraft Cockpit Lighting

  • Instrument Lighting
    • Instruments must be lit from a fixed installation and all items must be readable
    • Instrument lighting must be dimmable
  • Cabin Lighting
    • Passenger compartment must be adequately lit
    • Cockpit must be adequately lit for the study of charts and/or other documents

CAO 20.18 Appendix V

Cessna 172 VH-EWC

  • External Lights
    • Must have 1 landing light fitted for PVT & AWK ops (and CHTR without passengers), otherwise 2 landing lights
    • Position lights (nav lights), strobe lights and a rotating beacon
      • Red is left (port) wing
      • Green is right (starboard) wing
  • Other Lights
    • Shock proof torch (handheld or head-mounted), preferably emitting red light

Aeroplane Nav Lights Safety

Sensory Illusions

Sensory Illusions

Spatial Disorientation

ATSB

link to video

Overview

  • We are not here to scare you. But night flight can be dangerous if not done correctly
  • We rely on our senses to tell if we’re upright
  • Easy on the ground at 1G and easy during the day as we have a visual horizon to confirm what our inner ear is telling us
  • Not so easy at night when a visual horizon can be difficult to see
  • Always trust your instruments on a NVFR flight
  • If the suction gauge is in the green arc, your vacuum instruments are serviceable and should be relied upon for spatial orientation

The Vestibular System

Vestibular System

The Vestibular System

  • Consists of three semicircular canals in the inner ear which contains fluid — the otolith organs
  • These canals tell the brain if you’re upright, pitching, rolling or yawing
  • When your head moves, the fluid in the canals presses against tiny hairs, which transmit the sensation of movement to your brain
  • This can trick you into thinking you’re flying level when you’re banking
  • Trust your instruments — it is more likely they are right and you are wrong

The Leans

  • Caused by a sudden return to wings level after a bank gone unnoticed by the pilot
  • A slight bank may not be detectable by the inner ear
  • The pilot will now feel they are banking, when they are not, and correct the perceived bank
  • Trust your instruments — this cannot be stressed enough

Somatogravic Illusion

  • A rapid acceleration, such as experienced during take-off, stimulates the otolith organs in the same way as tilting the head backwards
  • This action creates the illusion of being in a nose-up attitude, especially in situations without good visual references
  • The disoriented pilot may push the aircraft into a nose-low or dive attitude
  • Trust your instruments

Coriolis Illusion

Man illusions

  • Sudden and intensely unpleasant tumbling
  • Causes cross-coupled stimulation of the semi-circular canals
  • The head movement means the canal that signalled yaw now sends a pitch message to the brain
  • A pilot may dive, bank or roll an aircraft under the influence of this illusion
  • Trust your instruments

Graveyard Spiral

Graveyard Spiral

  • When an aircraft begins to bank in cloud or dark night conditions
  • A constant rate of bank will be undetectable
  • Unless the pilot is watching the attitude indicator, there will be no visual clue
  • Attempts to pull out of the dive often only tighten the unrecognised turn and can cause aircraft to break up in flight

Black Hole Effect

Black Hole Effect

  • Where an approach is made to an airport remote from ground lighting
  • This fools pilots into thinking they are higher than they actually are, causing them to fly dangerously low approaches
  • Be cautious of your descent rate, trust your instruments and use the PAPI if available

Runway Slope Illusion

Runway Slope Illusion

Runway Width Illusion

Runway Width Illusion

Other Illusions

  • Autokinesis (objects appear to shift)
  • False reference (stars or lights near horizon)
  • Venus and Sirius (false aircraft)
  • Night myopia (dilation, inability to focus)

Other Illusions

  • Your brain is a powerful thing
  • But it can get things wrong
  • Trust your instruments

Night Vision

Night Vision

The Eye

The Eye

Rods and Cones

  • Rods are used during the night — they are unable to discern colours
  • Also distorts depth perception
  • Cones are used during the day

Maximising Night Vision

  • Avoid strong glare during the day, especially sand or snow
  • Avoid white light, especially fluoro lights — this is why we use red light in torches and cockpit lighting
  • Reduce cockpit lighting to maximise night vision
  • Do not look straight ahead into an oncoming light source
  • Night vision can take up to 30 minutes to be at maximum effectiveness

Factors Affecting Night Vision

  • Anything that reduces the amount of oxygen available in the bloodstream will also reduce night vision effectiveness
    • Smoking
    • Alcohol
    • Head cold
    • Altitude (especially above 4000ft AMSL)
    • Fatigue
    • Medication

Next Lesson

Ground Ops & Night Circuits

Landing RWY30 at night