Flying Notes

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Precision Approach ​

This page covers Task B. Precision Approach from the FAA-S-ACS-8C Instrument Rating Airplane Airman Certification Standards.

Objective ​

To determine the applicant exhibits satisfactory knowledge, risk management, and skills associated with performing precision approach procedures solely by reference to instruments.

Precision Approach Definition ​

Precision Instrument Approach

Uses a navigation system that provides lateral and vertical course guidance.

Types of Precision Approaches (PA) ​

  • Instrument Landing System (ILS)
    • The "standard" precision approach
    • Has localizer for lateral guidance and glideslope for vertical guidance
    • Requires equipment installed at the airport
  • Localizer Performance with Vertical guidance (LPV)
    • Is technically not a precision approach but rather an approach with vertical guidance (APV)
    • For our purposes these are flown just like precision approaches, but just have a different name
    • Are not precision approaches because they don't meet ICAO standards (Annex 10)
    • GPS equivalent of ILS
    • Same accuracy (width) as a localizer
    • Requires WAAS-GPS
    • LPV on GPS display
    • See overview section on GPS Approaches
  • Precision Approach Radar (PAR)
    • Dedicated radar site with two dishes, one horizontal and one vertical

Chart Review ​

  • Review KHEF ILS RWY 16L approach chart
  • A few notes
    • Triangle A and T
    • Note lighting and that is pilot controlled
      • See legend below
      • More on why this is important below
    • Note dark C for expanded circling radius
      • See legend in the Terminal Procedures Publication
    • Final approach fix for a precision is glideslope intercept given by lightning bolt symbol
    • Below profile view in the minimums strip
      • Altitudes MSL, visibility, then AGL
      • In parentheses for military
    • Note different approach categories
    • Note 3° glideslope and Threshold Crossing Height (TCH) of 58'
    • For us we are flying down to Decision Altitude (DA)
    • TDZE is defined as the highest elevation in the first 3,000 feet of the landing surface
    • Airport elevation is defined as the highest point of an airport's usable runways measured in feet from mean sea level.
Digital Terminal Procedures: KHEF ILS 16R IAP

Beginning a Precision Approach ​

  • Load the approach
    • Load the full approach and then if getting vectored press "activate vectors to final"
    • That way if ATC changes their mind about vectoring us and wants to send us to a point on the approach, it's already there and ready to go
    • Load the approach on the ground with the flight plan when able
  • Dial the localizer frequency into NAV radio
    • This should happen automatically when the approach is loaded
    • Recommend putting the ILS frequency into both NAV radios in case one fails
    • Glideslope comes with "for free"
  • Identify the localizer frequency
    • See morse code in plan view of approach chart
    • The G-1000 can identify it for us - see code next to NAV frequency

Flying an ILS ​

  • The Course Deviation Indicator (CDI) needle indicates where the course is relative to us
    • For example, if the course needle is to the right, the course is to our right
  • The glideslope diamond shows the location of the glideslope relative to us
    • For example, if the diamond is above center, the glideslope is above us
  • Localizer and glideslope signals get more sensitive the closer we get
  • Usually given a heading and told to intercept the localizer
    • Plan accordingly depending on heading given and winds
  • Intercept glideslope from below to avoid false glideslope
G1000 when flying ILS. Reference unknown.
Localizer course indications. FAA-H-8083-15B Instrument Flying Handbook Chapter 9: Navigation Systems Figure 9-38.

Precision Approach Procedures (Cessna 172S) ​

  • When cleared for approach
    • Taxi light on
    • If non-towered field, landing light on also
  • When established inbound
    • Mixture rich, timer zeroed
  • Half dot above GS/GP intercept
    • 1800 RPM, hold altitude
  • At flap speed
    • 10° of flaps
  • At GS/GP intercept
    • Adjust pitch to glideslope/glidepath, power to 80 KIAS
  • At FAF
    • Start timer, cross check altitude: "GS (or GP) verified"
    • Always start timer at FAF because a plane could enter the ILS critical area on ground and block glideslope, then you can keep flying as localizer approach
    • Also keeps you in habit so you never forget to start the timer when you do need to
  • When cleared to land
    • Landing light on
  • If criteria not met at Decision Altitude (DA)
    • Execute missed approach

Precision Approach Radar ​

Fort Worth Naval Air Station Joint Reserve Base radar approach minimums. The No-NOTAM MP: 1230-1530Z++ indicates planned maintanence during the time listed, where the conversion to local time is affected by daylight savings.
Quantico PAR.

Common Errors ​

  • Failure to have essential knowledge of the information on the instrument approach procedure chart
  • Incorrect communications procedures or noncompliance with ATC clearances
  • Failure to accomplish checklist items
  • Faulty basic instrument flying technique
  • Inappropriate application of DH/DA

Operational Errors ​

  • Failure to understand the fundamentals of ILS ground equipment, particularly the differences in course dimensions.
    • Since the VOR receiver is used on the localizer course, the assumption is sometimes made that interception and tracking techniques are identical when tracking localizer courses and VOR radials.
    • Remember that the CDI sensing is sharper and faster on the localizer course.
  • Disorientation during transition to the ILS due to poor planning and reliance on one receiver instead of on all available airborne equipment.
    • Use all the assistance available; a single receiver may fail.
  • Disorientation on the localizer course, due to the first error noted above.
  • Incorrect localizer interception angles.
    • A large interception angle usually results in overshooting and possible disorientation.
    • When intercepting, if possible, turn to the localizer course heading immediately upon the first indication of needle movement.
    • An ADF receiver is an excellent aid to orient you during an ILS approach if there is a locator or NDB on the inbound course.
  • Chasing the CDI and glidepath needles, especially when you have not sufficiently studied the approach before the flight.

Adherance to Stepdowns Prior to FAF ​

  • If the glideslope is flown prior to the final approach fix, the pilot is still required to adhere to altitude restrictions imposed by the stepdowns
  • See InFO 11009