How do I install the Oei Climb Gradient skill?

Run npx skillmds@latest add ashfordeou/oei-climb-gradient in your terminal (requires Node.js), paste this page's agent-chat prompt into Claude, Cursor, or any MCP-connected agent, or download the SKILL.md file and copy it into your agent's skills directory.

Is Oei Climb Gradient safe to use?

This skill has not completed SkillMD's automated safety review yet. SkillMD never runs a skill's scripts for you; review the SKILL.md before installing.

Which AI agents work with Oei Climb Gradient?

This skill is tagged as working with Claude Code, Claude.ai, OpenAI Codex. SKILL.md is an open format, so most agents that read a skills directory can load it too.

Is Oei Climb Gradient free to use?

Yes. Installing skills from SkillMD is free. This skill is licensed under Apache-2.

Who published Oei Climb Gradient?

ashfordeOU (@ashfordeou) published this skill. Their other Agent Skills are listed on their SkillMD profile.

Oei Climb Gradient by ashfordeou — Agent Skill

Name: Oei Climb Gradient
Author: ashfordeOU

Oei Climb Gradient

Use when you must compute the one engine inoperative climb gradient for a transport aircraft certification analysis: derate the total thrust to the remaining engines, derive the steady climb gradient from the excess thrust over the drag at the aircraft weight, convert the gradient fraction into percent and into a rate of climb, and compare the available gradient against the FAR-25.121 takeoff second segment, approach climb, and landing climb minimum values for the engine count of the twin, trijet, or quad transport. Produces the OEI thrust, the climb gradient in percent, the rate of climb, and the clearance verdict that gate the engine out performance assessment. Trigger: one engine inoperative, OEI, second segment, engine out, approach climb, landing climb, climb gradient.

ashfordeOU Updated Sep 17, 2026

File contents

One-Engine-Inoperative Climb Gradient (flight-mechanics/performance/oei-climb-gradient)

Use when the task is the engine out climb certification check for a transport aircraft: OEI thrust, climb gradient, rate of climb, and the FAR-25.121 minimum gradient clearance for the engine count.

Domain quick reference

OEI thrust from the engine count: T_oei = T_total * (n - f) / n, with total thrust T_total in newtons (N), n engines installed, and f engines failed (default 1). The remaining engines carry the derated thrust.
Steady climb gradient from the excess thrust: gamma = (T_oei - D) / W, with drag D and weight W in newtons (N); the result is a dimensionless fraction and percent equals fraction * 100.
Rate of climb from the gradient: ROC = gamma * V, with speed V in m/s and rate of climb in m/s. A climb exists only when T_oei is greater than D.
FAR-25.121 minimum gradients in percent with one engine inoperative (CS-25.121 mirrors the same tables):
- Second segment, takeoff configuration, gear up, at V2 (25.121(b)): 2.4 for 2 engines, 2.7 for 3 engines, 3.0 for 4 engines.
- Approach climb, gear down, go-around power (25.121(d)): 2.1 for 2 engines, 2.4 for 3 engines, 2.7 for 4 engines.
- Landing climb, all engines, landing configuration (25.121(e)): 3.2 for every engine count.
Engine out analysis sits in the FAR-25 / CS-25 transport performance certification context for takeoff and landing obstacle clearance checks.

Workflow

Collect the total installed thrust, the engine count, the drag in the configuration, the aircraft weight, and the speed.
Compute the OEI thrust with oei_thrust.
Compute the gradient fraction with climb_gradient and convert it to percent with gradient_percent.
Convert the gradient to a rate of climb with rate_of_climb.
Compare the gradient against second_segment_minimum, approach_climb_minimum, or landing_climb_minimum for the engine count with meets_minimum before gating.
Check that the OEI thrust exceeds the drag; a negative gradient means the configuration cannot climb.

Pitfalls

Using all-engine thrust instead of the OEI thrust: the certification check uses the remaining engines only, so derate by (n - f) / n before computing the gradient.
Mixing weight units: W must be the weight in newtons (mass * g0), not the mass in kg, or the gradient fraction comes out wrong.
Applying the wrong minimum to the wrong segment: the second segment, approach, and landing climbs have different tables (25.121(b), (d), (e)), and the engine count selects the value within each table.
Treating a negative gradient as an error: a negative result is a legitimate no-climb verdict, not a computation failure.
Using an engine count outside 2 to 4: the FAR-25.121 minimum tables cover twin, trijet, and quad configurations only.

Behavior contract (gate 3)

The OEI thrust, gradient, rate of climb, and minimum clearance logic is exercised by the gate 3 contract test: scripts/test_oei_climb_gradient.py against scripts/oei_climb_gradient_logic.py (stdlib unittest, offline). Run: python3 scripts/test_oei_climb_gradient.py

Compliance

Standards referenced, not reproduced: FAR-25 is US government work (public domain) and CS-25 is a free EASA download; the one-engine-inoperative climb gradient method and the 25.121 minimum values are common flight-mechanics methodology, summary-only per standards-map.yaml.
compliance: STANDARDS-REF, gated: false.

---name: oei-climb-gradientdescription: Use when you must compute the one engine inoperative climb gradient for a transport aircraft certification analysis: derate the total thrust to the remaining engines, derive the steady climb gradient from the excess thrust over the drag at the aircraft weight, convert the gradient fraction into percent and into a rate of climb, and compare the available gradient against the FAR-25.121 takeoff second segment, approach climb, and landing climb minimum values for the engine count of the twin, trijet, or quad transport. Produces the OEI thrust, the climb gradient in percent, the rate of climb, and the clearance verdict that gate the engine out performance assessment. Trigger: one engine inoperative, OEI, second segment, engine out, approach climb, landing climb, climb gradient.license: Apache-2.0---# One-Engine-Inoperative Climb Gradient (flight-mechanics/performance/oei-climb-gradient)Use when the task is the engine out climb certification check fora transport aircraft: OEI thrust, climb gradient, rate of climb,and the FAR-25.121 minimum gradient clearance for the enginecount.## Domain quick reference- OEI thrust from the engine count: T_oei = T_total * (n - f) / n, with total thrust T_total in newtons (N), n engines installed, and f engines failed (default 1). The remaining engines carry the derated thrust.- Steady climb gradient from the excess thrust: gamma = (T_oei - D) / W, with drag D and weight W in newtons (N); the result is a dimensionless fraction and percent equals fraction * 100.- Rate of climb from the gradient: ROC = gamma * V, with speed V in m/s and rate of climb in m/s. A climb exists only when T_oei is greater than D.- FAR-25.121 minimum gradients in percent with one engine inoperative (CS-25.121 mirrors the same tables): - Second segment, takeoff configuration, gear up, at V2 (25.121(b)): 2.4 for 2 engines, 2.7 for 3 engines, 3.0 for 4 engines. - Approach climb, gear down, go-around power (25.121(d)): 2.1 for 2 engines, 2.4 for 3 engines, 2.7 for 4 engines. - Landing climb, all engines, landing configuration (25.121(e)): 3.2 for every engine count.- Engine out analysis sits in the FAR-25 / CS-25 transport performance certification context for takeoff and landing obstacle clearance checks.## Workflow1. Collect the total installed thrust, the engine count, the drag in the configuration, the aircraft weight, and the speed.2. Compute the OEI thrust with oei_thrust.3. Compute the gradient fraction with climb_gradient and convert it to percent with gradient_percent.4. Convert the gradient to a rate of climb with rate_of_climb.5. Compare the gradient against second_segment_minimum, approach_climb_minimum, or landing_climb_minimum for the engine count with meets_minimum before gating.6. Check that the OEI thrust exceeds the drag; a negative gradient means the configuration cannot climb.## Pitfalls- Using all-engine thrust instead of the OEI thrust: the certification check uses the remaining engines only, so derate by (n - f) / n before computing the gradient.- Mixing weight units: W must be the weight in newtons (mass * g0), not the mass in kg, or the gradient fraction comes out wrong.- Applying the wrong minimum to the wrong segment: the second segment, approach, and landing climbs have different tables (25.121(b), (d), (e)), and the engine count selects the value within each table.- Treating a negative gradient as an error: a negative result is a legitimate no-climb verdict, not a computation failure.- Using an engine count outside 2 to 4: the FAR-25.121 minimum tables cover twin, trijet, and quad configurations only.## Behavior contract (gate 3)The OEI thrust, gradient, rate of climb, and minimum clearancelogic is exercised by the gate 3 contract test:scripts/test_oei_climb_gradient.py againstscripts/oei_climb_gradient_logic.py (stdlib unittest, offline).Run:python3 scripts/test_oei_climb_gradient.py## Compliance- Standards referenced, not reproduced: FAR-25 is US government work (public domain) and CS-25 is a free EASA download; the one-engine-inoperative climb gradient method and the 25.121 minimum values are common flight-mechanics methodology, summary-only per standards-map.yaml.- compliance: STANDARDS-REF, gated: false.

Frequently asked questions