| name | fee-analysis |
| description | Use when advertised flight price seems too good, or when comparing LCC vs legacy carrier total costs. Triggers on hidden fees, baggage cost, true price, real cost, checkout surprise. |
Fee Analysis - Phân Tích và Loại Bỏ Phí Phụ Thu
Purpose
Airlines - especially LCCs - intentionally show low base fares then add fees at checkout. This skill strips away the deception, calculates what you'll actually pay, and re-ranks options by true cost. A $89 Spirit ticket that becomes $275 after fees loses to a $189 Southwest that includes everything.
Input Required
flight_options[] from flight-search skillbaggage from traveler profile (carry_on | checked_1 | checked_2)loyalty_programs[] from traveler profilepreferred_payment (credit card type, if known)
Execution Steps
Step 1: Load Airline Fee Matrix
Read references/airline-fee-matrix.md for comprehensive fee data by airline.
Step 2: Calculate True Total for Each Option
For each flight option, compute:
true_total = base_fare
+ taxes_and_surcharges
+ carry_on_fee (if LCC and carry_on not included)
+ checked_bag_fee (× number of bags × number of passengers)
+ seat_selection_fee (if desired, per passenger)
+ meal_fee (if not included, long-haul)
+ change_fee_risk (weighted by probability from flexibility-analysis)
+ payment_surcharge (credit card fee if applicable)
Step 3: Fee Breakdown Table
Present each option with full fee breakdown:
Fee Breakdown: HAN → SFO, 2 Adults + 1 Child
Option A (VietJet) Option B (VN Airlines) Option C (Korean Air)
Base Fare $380 × 3 = $1,140 $620 × 3 = $1,860 $580 × 3 = $1,740
Tax & Surcharge $95 × 3 = $285 $120 × 3 = $360 $110 × 3 = $330
Carry-on (7kg) Included Included Included
Checked Bag (23kg) $45 × 3 = $135 Included Included
Seat Selection $12 × 3 = $36 Free $15 × 3 = $45
Meal Not included Included Included
Payment Fee $0 (debit) $0 $0
─────────────────────────────────────────────────────────────────────────
TRUE TOTAL $1,596 $2,220 $2,115
Per Person $532 $740 $705
Rank Change Was #1 → Still #1 Was #3 → Now #3 Was #2 → Now #2
Step 4: Identify Rank Reversals
Critical insight: When true_total changes the ranking from advertised price:
⚠️ RANK REVERSAL DETECTED:
Option X was ranked #3 by advertised price ($89)
After fees, it's actually #5 ($275)
Option Y was ranked #5 by advertised price ($189)
After fees, it's actually #2 ($189) - no hidden fees!
Step 5: Fee Avoidance Strategies
For each applicable fee, provide actionable avoidance advice:
Carry-on Fee (LCC):
- Pack within airline's free personal item dimensions
- VietJet: 7kg carry-on included; Spirit: personal item only (45×35×20cm)
- Consider: Is the carry-on fee still cheaper than a legacy carrier total?
Checked Bag Fee:
- Airline credit card: Many waive first bag (e.g., United Explorer card)
- Status match: Silver/Gold loyalty = free bags
- Pre-pay online: Always cheaper than airport counter (20-50% savings)
- Ship luggage separately: Services like LuggageForward for long trips
Seat Selection Fee:
- Skip it: Accept random assignment for savings
- Check in exactly at 24h mark: Best free seats available
- Back of plane: Often free even when front costs extra
Change/Cancel Fee:
- Book with credit card that offers trip protection
- Some airlines (Southwest, JetBlue) offer free changes
- 24-hour rule: Most US carriers allow free cancellation within 24h of booking
Payment Surcharge:
- Use debit card (many airlines waive surcharge)
- Some airlines charge extra for credit card (Ryanair, AirAsia)
- PayPal sometimes adds processing fees
Step 6: Cabin Bag Size Reference
Include for options with strict carry-on policies:
| Airline | Personal Item | Cabin Bag | Weight Limit |
|---|
| VietJet | 36×23×56cm | 7kg total | 7kg |
| AirAsia | 40×30×10cm | 54×38×23cm (paid) | 7kg |
| Spirit | 45×35×20cm | 56×46×25cm (paid) | None stated |
| Ryanair | 40×20×25cm | 55×40×20cm (paid) | 10kg |
| Southwest | No limit | 61×41×28cm | None stated |
| Vietnam Airlines | 56×36×23cm | 12kg (economy) | 12kg |
Step 7: Output Summary
ORIGINAL RANKING (by advertised price):
1. VietJet $380 2. Korean $580 3. VN Airlines $620
TRUE RANKING (all fees included):
1. VietJet $532 2. Korean $705 3. VN Airlines $740
VERDICT: VietJet remains cheapest even after fees (+$152 in extras).
However, VN Airlines includes lounge access with Business Saver
that isn't captured in this analysis.
Limitations
- Fee data is based on published policies - airlines may change without notice
- Some fees vary by route, booking channel, or time of purchase
- Loyalty status benefits are estimated - check your specific tier
- Meal costs for LCCs are not included (varies too widely)
