Diversions

Introduction:

  • Diversions are deviations an intended flight plan due to an unexpected circumstance or flight system performance
  • Situations may develop in flight which require a pilot to divert, including pilot comfort, environmentals, and aircraft condition
  • While pilots do not takeoff with the intent to divert, pilots must plan for viable diverts with the necessary resources to facilitate safe operation
  • Arguably, the most important step in diversions is deciding to divert in the first place
  • Once the decision is made, pilots will execute either a Visual Flight Rules or Instrument Flight Rules diversion procedure
  • Practice develops skills necessary for plotting a new course and determining a new ETA while en route
  • Be careful to avoid common errors associated with diversion
  • Although the concept is the same, their procedures can be dramatically different when flying Visual Flight Rules (VFR) or Instrument Flight Rules (IFR)
  • When you have a solid understanding of diversions, compare your knowledge against the Private Pilot (Airplane) or Commercial Pilot (Airplane) Airman Certification Standards

Situations Requiring a Deviation:

  • No pilot plans for to divert; however, there are several situations that can lead to executing a divert, including:
    • Personal minimums exceeded (fatigue, illness)
    • Aircraft performance limitations exceeded (winds, system malfunction, etc.)
    • Inaccurate planning (low fuel)
    • Poor weather
    • Airport closure
    • Change in mission
  • Part of preflight planning requires identifying those situations that may be present and to prepare for that contingency

Diversion Planning:

  • Not every airport is a suitable divert
  • An alternate destination must be first and foremost a location that could overcome the challenges expected or likely at your original destination
  • It must be reachable, in that you have the required fuel plus reserves
  • When planning, consider a pre-filled out data card which includes:
    • Airport name, including the identifier for entering into automated flight systems
    • Airport Diagram/layout for familiarity
      • Multiple runways (less likely both can be closed due to unknown factors like a disabled aircraft)
    • Frequencies required to comply with airspace/ATC requirements
    • NAVAIDs to help identify the airfield
    • Approaches available, if IFR
    • Any unusable runways, approaches, or clearances (such as LAHSO), you cannot accept if offered
    • Services available, especially considering a maintenance related divert
    • General performance expectations based on time/distance from destination
      • Think fuel, time, etc.
      • In the airplane you may be forced to make generalized calculations in the interest of time, but here you can be more accurate

Diversion Decision-Making:

  • No one wants to divert, but proper planning provides a suitable option
  • When you set your personal minimums for the day, ensure they incorporate aeronautical decision-making on when to accept a diversion
  • Diversions need not be empirical, that is, they don't need to be quantified by numbers, approach speeds, etc.
    • If uncomfortable with a situation, divert!

VFR Diversion Procedure:

  • Note the time
  • Verify the airplane's present position
  • Determine the location of the new destination
  • Turn in the appropriate direction to an estimated/initial heading, taking into consideration: airspace, obstructions, and/or adverse weather
    • An initial turn promptly initiates the diversion until more precise information can be determined
  • Determine the distance and more exact compass heading to the new destination
    • Distance:
      • Plotter
      • Mileage scale on chart
      • 1 min of latitude = 1 NM
    • Compass Heading
      • Use compass rose on VOR on map
  • Turn to the compass heading
  • Select prominent land marks to aid in flying the new course
  • Compute ETE, ETA, and the fuel required to reach the new destination
  • Contact FSS to amend your flight plan
  • Note that when diverting to a nearby airport (25 NM or less) and fuel is not critical, make reasonably accurate estimates rather than performing actual computations

IFR Diversion Procedure:

  • Determine new destination
  • Request a clearance
    • This is going to sound identical to picking up an IFR clearance (even though you're already operating on one) in air
  • Execute new clearance

Diversion Common Errors:

  • En-Route Airport Legend
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  • Failure to note the time
  • Unaware of fuel before diversion
  • Improper calculations
  • Forgetting to turn toward estimated heading
  • Getting lost
  • En-Route Airport Legend
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Private Pilot (Airplane) Diversion Airman Certification Standards:


Private Pilot (Airplane) Diversion Knowledge:

The applicant demonstrates an understanding of:

Private Pilot (Airplane) Diversion Risk Management:

The applicant is able to identify, assess, and mitigate risk associated with:

  • PA.VI.C.R1:

    Collision hazards.

  • PA.VI.C.R2:

    Distractions, task prioritization, loss of situational awareness, or disorientation.

  • PA.VI.C.R3:

    Circumstances that would make diversion prudent.

  • PA.VI.C.R4:

    Selecting an appropriate airport or seaplane base.

  • PA.VI.C.R5:

    Using available resources (e.g., automation, ATC, and flight deck planning aids).

Private Pilot (Airplane) Diversion Skills:

The applicant exhibits the skills to:

  • PA.VI.C.S1:

    Select a suitable destination and route for diversion.

  • PA.VI.C.S2:

    Make a reasonable estimate of heading, groundspeed, arrival time, and fuel required to the "divert to" destination.

  • PA.VI.C.S3:

    Maintain the selected altitude ±200 feet and heading ±15°.

  • PA.VI.C.S4:

    Update/interpret weather in flight.

  • PA.VI.C.S5:

    Use displays of digital weather and aeronautical information, as applicable to maintain situational awareness.

  • PA.VI.C.S6:

    Promptly divert toward the destination.

Commercial Pilot (Airplane) Diversion Airman Certification Standards:


Commercial Pilot (Airplane) Diversion Knowledge:

The applicant demonstrates an understanding of:

Commercial Pilot (Airplane) Diversion Risk Management:

The applicant is able to identify, assess, and mitigate risk associated with:

  • CA.VI.C.R1:

    Collision hazards.

  • CA.VI.C.R2:

    Distractions, task prioritization, loss of situational awareness, or disorientation.

  • CA.VI.C.R3:

    Circumstances that would make diversion prudent.

  • CA.VI.C.R4:

    Selecting an appropriate airport or seaplane base.

  • CA.VI.C.R5:

    Using available resources (e.g., automation, ATC, and flight deck planning aids).

Commercial Pilot (Airplane) Diversion Skills:

The applicant exhibits the skills to:

  • CA.VI.C.S1:

    Select a suitable destination and route for diversion.

  • CA.VI.C.S2:

    Make a reasonable estimate of heading, groundspeed, arrival time, and fuel required to the “divert to" destination.

  • CA.VI.C.S3:

    Maintain the selected altitude ±100 feet and heading ±10°.

  • CA.VI.C.S4:

    Update/interpret weather in flight.

  • CA.VI.C.S5:

    Use displays of digital weather and aeronautical information, as applicable to maintain situational awareness.

  • CA.VI.C.S6:

    Promptly divert toward the destination.

Diversions Case Studies:

Conclusion:

  • The decision to divert cannot be made too soon
    • Many pilots have put themselves into avoidable situations by pushing a situation that they knew to be bad
  • Consider flying into common divert airports before needed for an emergency or detereorating weather
  • When traveling cross-country, it is recommended to carry extra closes/toiletries (bingo bag) to mitigate comfort-based delays when making diversion decisions
  • When making alterations due to weather, lateral deviations of 10 or 20° of course made early enough can be made to preclude a full re-work of the previously planned flight
  • Don't just select diversion options, ensure you're familiar enough with the field to ensure a smooth transition from the original plan
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References: