Defence & Aerospace · Commercial Aerospace
Backlog and the Narrowbody Ramp
How to derive aircraft backlog-years and book-to-bill from filed orders and deliveries, and read them against production-rate targets for the narrowbody ramp.
Selborne Research · Commercial Aerospace coverage: 7 guides, 6 company profiles, a primer and Excel model
Educational analysis. This guide is not investment advice or a recommendation to buy or sell any security, and it is not personalised.
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Backlog-Years Tell You How Long the Ramp Runs
Aircraft OEM equity work hinges on two linked stocks: firm order backlog (units and dollar value) and the production rate converting that backlog into deliveries. Backlog-years bridges them: undelivered firm orders divided by annual deliveries. It is always derived, never OEM headline guidance. Analysts compute it to sanity-check whether stated monthly rates can clear the order book inside a credible horizon.
FY2025 narrowbody maths from filed data: Boeing 737 ~9.9 years (4,404 undelivered firm orders ÷ 447 deliveries); Airbus A320 Family ~11.8 years (7,151 backlog ÷ 607 deliveries). Both sit inside our 8-12 year healthy screening range on narrowbody programmes.
FY2025 Backlog and Delivery Snapshot
| Metric | Boeing | Airbus |
|---|---|---|
| Commercial backlog (units) | >6,100 aircraft | 8,754 aircraft |
| BCA / commercial order book (value) | $567.3B | €539.7B (commercial division) |
| FY2025 deliveries | 600 (737: 447) | 793 (A320 Family: 607) |
| Derived total backlog-years | ~10.2 yr | ~11.0 yr |
| Derived narrowbody backlog-years | 737: ~9.9 yr | A320 Family: ~11.8 yr |
| FY2025 book-to-bill (commercial units) | ~1.96× | ~1.12× |
| Production-rate target | 737: 42/month (Q4 2025) | A320: 70-75/month by end-2027 |
Boeing’s unit book-to-bill is the strongest in the peer set; Airbus runs a larger absolute backlog with a lower but still healthy ratio above 1.0. Dollar book-to-bill is not disclosed by Boeing; Airbus files company-wide value book-to-bill above 1.
Backlog-Years Screen
Screening bands for derived backlog-years on narrowbody programmes:
| Band | Years | Read |
|---|---|---|
| Caution | <6 yr | Demand or execution gap |
| Healthy | 8-12 yr | BA and AIR FY2025 points sit here |
| Stretched | >14 yr | Delivery-credibility risk |
Both FY2025 points computed above sit inside that band. That says nothing about near-term execution: rate ramps, supplier bottlenecks and certification caps still govern how fast the backlog actually clears. Backlog-years is a stock measure; book-to-bill, below, is the flow check.
Book-to-Bill: Orders Versus Deliveries
Book-to-bill is net orders (or order intake) divided by deliveries in the period. Definitions differ by filer; use the same numerator and denominator the company uses.
| Company | FY2025 ratio | Computation |
|---|---|---|
| Boeing (commercial units) | ~1.96× | 1,173 net orders ÷ 600 deliveries |
| Airbus (commercial units) | ~1.12× | 889 net orders ÷ 793 deliveries |
| GE Aerospace | ~1.44× | $66.2B orders ÷ $45.855B revenue |
We screen book-to-bill at <0.95 contracting; 0.95-1.05 steady; >1.05 growth; above 1.0 healthy. All three computed commercial peers exceed 1.0 in FY2025. Safran and Howmet do not disclose group book-to-bill in primary filings.
Production-Rate Ramp
Monthly production rate is the conversion lever linking backlog to revenue:
| Programme | FY2025 rate / target | Source basis |
|---|---|---|
| Boeing 737 | 42/month (end Q4 2025) | FY2025 earnings release |
| Boeing 787 | Transitioning to 8/month | FY2025 release |
| Airbus A320 Family | 70-75/month by end-2027; stabilise 75 | Feb 2026 outlook |
| Safran LEAP | 1,802 deliveries FY2025; FY2026 plan ~+15% | FY2025 results |
Rate increases pull forward revenue, and working capital, supplier stress and quality oversight come with them. Boeing’s climb follows a prolonged production trough; Airbus is scaling from an already larger delivery base.
Engine Backlog Follows the Airframe Ramp
Safran does not file a LEAP order backlog in units, so the FY2025 delivery count above is the only public throughput signal. CFM/LEAP volumes follow Airbus A320neo and Boeing 737 MAX output. The Safran profile covers Propulsion aftermarket at 64.6% of revenue and 23.0% recurring operating margin, the engine side of the same ramp.
Where This Shows Up in Filings
Boeing’s FY2025 FCF was ($1.9B), negative even with deliveries running at the pace shown above: that is the production-trough case worked through in the Boeing profile.
Airbus’s FY2025 FCF was €4.8B, with €12.2B net cash and a 10.4% Commercial Aircraft EBIT Adjusted margin: the same ramp, from a stronger starting balance sheet, in the Airbus profile.
The duopoly guide covers why Boeing plus Airbus still control 86% of 2024 global deliveries and why certification barriers sustain the order concentration you see in these backlog tables.
Building the Ramp in a Model
- Pull backlog units and deliveries from the same fiscal period before computing backlog-years.
- Label backlog-years derived; do not present as management guidance.
- Cross-check book-to-bill above 1.0 against backlog unit growth year-on-year.
- Layer stated monthly rate targets and sensitivity on supplier/quality delays.
- For engine suppliers, map LEAP or CFM delivery growth to airframe delivery guidance.
Commercial Aerospace Sector Primer
Delivery rates and the aftermarket annuity are the inputs. This primer takes them to a dual-rate sum-of-the-parts and an EV/EBITDA you can defend.
- 15 sections, original equipment and aftermarket valued apart
- 40 pages
- OEM airframer and engine OEM, dual-rate sum-of-the-parts
- 2 worked valuations
- backlog-years, book-to-bill, aftermarket mix, free cash flow
- 6-company screen
The Excel model is the primer's two dual-rate sum-of-the-parts builds live across 12 sheets: original equipment capitalised at a cyclical rate, the installed-base aftermarket at a lower annuity rate, summed to enterprise value. Change the delivery rate, the aftermarket dollars per unit or either discount rate and the value per share moves.
See what's in the Commercial Aerospace Sector Primer →£25 PDF · £59 with the Excel model · £159 for all three Defence & Aerospace industries
Frequently Asked Questions
- How do you calculate aircraft backlog-years?
- Backlog-years is a derived metric: undelivered firm orders (units) divided by annual deliveries in the same period. Boeing 737: 4,404 undelivered firm orders ÷ 447 FY2025 deliveries = ~9.9 years. Airbus A320 Family: 7,151 backlog ÷ 607 deliveries = ~11.8 years. OEMs publish backlog units and delivery counts; they do not publish headline backlog-years as official guidance.
- What is a healthy backlog-years range for narrowbody programmes?
- A working convention treats 8-12 years as healthy on narrowbody programmes. Below 6 years signals demand or execution gap risk; above 14 years raises delivery-credibility risk. The FY2025 derived points sit inside the healthy band: Boeing 737 ~9.9 yr, Airbus A320 Family ~11.8 yr.
- What production rates are Boeing and Airbus targeting?
- Boeing reached 737 production at 42/month by end Q4 2025. Airbus targets A320 Family production at 70-75/month by end-2027, stabilising at 75/month. Safran delivered 1,802 LEAP engines in FY2025 (+28% YoY) with a FY2026 plan of roughly +15%. Rate targets link backlog conversion to near-term revenue and working capital.
- What were FY2025 book-to-bill ratios for Boeing and Airbus?
- Boeing commercial units: 1,173 net orders ÷ 600 deliveries = ~1.96× (computed; not labelled in the filing). Airbus commercial units: 889 net orders ÷ 793 deliveries = ~1.12× (computed). A working convention treats above 1.0 as healthy; below 0.95 as contracting. Both commercial peers exceeded 1.0 in FY2025.
Read next
Boeing/Airbus Duopoly Economics
Why Boeing and Airbus still control 86% of 2024 deliveries, certification and production-cap barriers, sole-source supplier lock-in, and why transaction-level airframe pricing stays off the filing record.
OEM vs Aftermarket: Where Aerospace Makes Money
Why commercial aerospace margins split between loss-making OE ramps and high-margin aftermarket: Boeing BCA −17.1% vs BGS ~18.5%, GE 71% services at 26.6% CES margin, and the ~15-25 pp aftermarket premium.
Firm Backlog vs Unfilled Orders in Aerospace
What Boeing's ASC 606 backlog test excludes, how Airbus applies the same test under IFRS 15, and why GE files the number as RPO.
See it applied
These company profiles apply the concepts from this guide to real public companies.