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Weight & Balance (Mobile)

Run a weight-and-balance calculation for any of your aircraft, on the kneeboard, before each flight. The mobile W&B is feature-equivalent to the web — the same arms, the same envelopes, the same private-passenger config — just touch-optimized.

What it does

For each loading scenario, the W&B calculator:

  1. Pulls the station arms and gross-weight limit from the aircraft's POH config (set once, reused forever)
  2. Adds your fuel and oil quantities
  3. Adds passengers and baggage at the correct stations
  4. Computes the total weight and the center of gravity in inches aft of datum
  5. Plots the result on the aircraft's CG envelope to show in-or-out

If the result falls outside the envelope, you'll see a warning before you fly.

The aircraft's POH config

Each aircraft has a configurable W&B profile — set once on the web (or via the Configurations sub-page on mobile). The profile holds:

  • Empty weight + arm
  • Fuel station(s) with arms and gallon-to-pound conversion
  • Oil station with arm and quart-to-pound conversion
  • Multiple seat rows — pilot/co-pilot, middle row, rear row, etc., each with its own arm
  • Multiple luggage areas — front baggage, rear baggage, hat shelf
  • CG envelope — series of points defining the aircraft's allowable CG range across gross weights
  • Maximum gross weight
  • Maximum landing weight

Profile data lives on the server and syncs to mobile. Edit on either; both update.

A typical scenario

  1. Open Weight & Balance tile
  2. Select aircraft (defaults to last-used)
  3. Set fuel in gallons (slider or numeric input)
  4. Set oil in quarts
  5. Tap + Add Passenger for each seat occupant
  6. Choose seat row / arm
  7. Enter weight
  8. Private weight toggle — if you mark a passenger as private, the weight is stored separately and doesn't display in the visible total. Useful for spouses / sensitive cases. The math still uses the real value.
  9. Add baggage as needed
  10. Read the result:
  11. Total weight: red if over gross
  12. CG: red if outside envelope
  13. Envelope plot: dot shows your loading vs. the polygon

You can also save the loading as a scenario (e.g., "Solo + golf clubs", "Family of four with full fuel") for one-tap recall.

Private passenger weight

This is the feature that took several iterations to get right. The use case: a pilot wants to record a passenger's weight (because it affects the math) but doesn't want the value visible on a screen during boarding.

How it works:

  • Toggle Private on a passenger row
  • The weight input changes — your typed value is saved to a separate hidden slotPrivateWeight field
  • The displayed value in the row stays blank or (private)
  • The CG / total math uses the real value
  • Re-opening a saved scenario remembers the private-marked rows

Behind the scenes the private weight is local to the device; it's not synced.

Multiple seat rows / luggage areas

Aircraft like a Cessna 182 or Piper Cherokee Six have several station arms worth tracking:

  • Front seats at one arm
  • Middle row at another
  • Rear row at yet another
  • Front baggage at a forward arm (helps balance heavy fuel loadings)
  • Rear baggage at an aft arm
  • Hat shelf very far aft

The W&B config lets you add as many rows as the POH defines. The mobile view stacks them vertically so you can scroll through and enter weights without horizontal cramping.

Oil quantity

Often overlooked but it counts — 8 quarts of oil at the typical engine arm adds about 15 lb at a forward CG. The W&B includes an oil field separately from fuel; set it to your typical level (most owners run their engine at ~1 qt below max).

Saving and recalling scenarios

Tap Save Scenario to store a loading by name. Tap Load Scenario to recall. Common saves:

  • "Empty trip" — just you + minimal fuel for a check ride
  • "Cross-country full" — you + spouse + bags + full fuel
  • "Maintenance ferry" — you only, ferry tanks if applicable
  • "Type-rating practice" — you + CFI + full fuel

Scenarios sync between web and mobile.

CG envelope plot

The plot shows:

  • The aircraft's CG envelope (polygon, defined per aircraft)
  • Your current loading (a dot)
  • The arrow / trace if you've moved through several scenarios

If you're inside the envelope: green dot. If you're outside: red dot and a banner explaining which limit was busted (forward CG, aft CG, gross weight).

Pilots — start the flight from this screen

When the loading is good (green dot, total under gross), the Save & File Flight button at the bottom takes you to the pilot logbook entry form with the aircraft pre-selected. The W&B record itself isn't saved with the flight (yet — on the roadmap).