{"id":2420,"date":"2025-10-18T19:19:02","date_gmt":"2025-10-18T17:19:02","guid":{"rendered":"https:\/\/acriv.org\/WP\/?page_id=2420"},"modified":"2025-10-18T19:19:02","modified_gmt":"2025-10-18T17:19:02","slug":"ifr-tips","status":"publish","type":"page","link":"https:\/\/acriv.org\/WP\/ifr-tips\/","title":{"rendered":"IFR : TIPS"},"content":{"rendered":"\n

<\/p>\n\n\n\n

<\/p>\n\n\n\n

\ud83e\uddee Les r\u00e9f\u00e9rences de calcul mental IFR<\/strong><\/h1>\n\n\n\n

(valables pour petits avions IFR, monomoteurs, IR(A), CB-IR)<\/em><\/p>\n\n\n\n

\n\n\n\n

\u2708\ufe0f 1. Gestion du plan de descente (le plus important)<\/h2>\n\n\n\n

\ud83c\udfaf Objectif :<\/h3>\n\n\n\n

Savoir quand commencer sa descente<\/strong> et \u00e0 quel taux<\/strong> descendre pour suivre un plan (g\u00e9n\u00e9ralement 3\u00b0).<\/p>\n\n\n\n

\n\n\n\n

\ud83d\udd39 A. R\u00e8gle des 3 % \/ 3\u00b0<\/strong><\/h3>\n\n\n\n

Plan standard : 3\u00b0 = 5 % = 300 ft\/NM<\/strong>
\u27a1\ufe0f Chaque mille nautique parcouru = ~300 ft de descente.<\/p>\n\n\n\n

Formule :<\/strong> <\/p>\n\n\n

\n
\"\"<\/figure>\n<\/div>\n\n\n

Exemple :<\/strong>
Tu es \u00e0 6000 ft, piste 0 ft :
\u2192 6000 \u00f7 300 = 20 NM avant le seuil<\/strong> pour commencer ta descente \u00e0 3\u00b0.<\/p>\n\n\n\n

\n\n\n\n

\ud83d\udd39 B. Taux de descente (ft\/min)<\/strong><\/h3>\n\n\n\n

Formule :<\/strong> <\/p>\n\n\n

\n
\"\"<\/figure>\n<\/div>\n\n\n

Exemples :<\/p>\n\n\n\n

Vsol (kt)<\/th>VS pour 3\u00b0<\/th><\/tr><\/thead>
90 kt<\/td>450 ft\/min<\/td><\/tr>
120 kt<\/td>600 ft\/min<\/td><\/tr>
150 kt<\/td>750 ft\/min<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

\ud83e\udde0 Astuce : tu peux retenir simplement \u201cla moiti\u00e9 de ta vitesse \u00d710\u201d<\/em><\/p>\n\n\n\n

\n

Ex : 120 kt \u2192 moiti\u00e9 = 60 \u2192 \u00d710 = 600 ft\/min<\/strong>.<\/p>\n<\/blockquote>\n\n\n\n

\n\n\n\n

\ud83d\udd39 C. Quand amorcer la descente ?<\/strong><\/h3>\n\n\n\n

Formule pratique :<\/strong><\/p>\n\n\n

\n
\"\"<\/figure>\n<\/div>\n\n\n

ou plus rapide :<\/p>\n\n\n\n

\n

Altitude \u00e0 perdre \/ 1000 \u00d7 3<\/p>\n<\/blockquote>\n\n\n\n

Exemple :
De 8000 ft \u00e0 2000 ft (\u2192 perte 6000 ft)
\u2192 6 \u00d7 3 = 18 NM avant le point d\u2019arriv\u00e9e<\/strong>.<\/p>\n\n\n\n

\n\n\n\n

\ud83d\udd39 D. Descente plus ou moins forte<\/strong><\/h3>\n\n\n\n
    \n
  • 2,5\u00b0 \u2192 250 ft\/NM<\/li>\n\n\n\n
  • 3,5\u00b0 \u2192 350 ft\/NM<\/li>\n\n\n\n
  • 4\u00b0 \u2192 400 ft\/NM
    \ud83d\udc49 Utile pour adapter un profil selon le vent ou le relief.<\/li>\n<\/ul>\n\n\n\n
    \n\n\n\n

    \ud83e\udded 2. Cap, d\u00e9rive et vent de travers<\/h2>\n\n\n\n

    \ud83d\udd39 A. Vent de travers (Crosswind)<\/strong><\/h3>\n\n\n\n

    Vent de travers\u2248Vent total\u00d7sin\u2061(angle)\\text{Vent de travers} \u2248 \\text{Vent total} \u00d7 \\sin(\\text{angle})Vent de travers\u2248Vent total\u00d7sin(angle)<\/p>\n\n\n\n

    \ud83d\udca1 En pratique, retiens :<\/p>\n\n\n\n

    Angle vent\/piste<\/th>% de vent de travers<\/th><\/tr><\/thead>
    30\u00b0<\/td>50 %<\/td><\/tr>
    45\u00b0<\/td>70 %<\/td><\/tr>
    60\u00b0<\/td>85 %<\/td><\/tr>
    90\u00b0<\/td>100 %<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

    xemple : vent 20 kt \u00e0 45\u00b0 \u2192 composante traversi\u00e8re \u2248 14 kt.<\/p>\n\n\n\n

    \n\n\n\n

    \ud83d\udd39 B. D\u00e9rive (Wind Correction Angle)<\/strong><\/h3>\n\n\n
    \n
    \"\"<\/figure>\n<\/div>\n\n\n

    Mais pour le calcul mental rapide :<\/p>\n\n\n

    \n
    \"\"<\/figure>\n<\/div>\n\n\n

    Trop complexe ?
    \ud83d\udc49 Simplifie : 1\u00b0 de d\u00e9rive pour 10 kt de vent de travers \u00e0 100 kt<\/strong>.
    Exemple : vent de travers 20 kt, vitesse 100 kt \u2192 \u22482\u00b0 de correction<\/strong>.<\/p>\n\n\n\n

    \n\n\n\n

    \u23f1\ufe0f 3. Temps \/ distance \/ vitesse (la r\u00e8gle du 60)<\/h2>\n\n\n\n

    La \u201cRule of 60<\/strong>\u201d est LA r\u00e8gle de base IFR.<\/p>\n\n\n\n

    \n

    \u00c0 60 kt \u2192 1 NM\/min.
    Donc : 1 NM = 1 minute \u00e0 60 kt.
    Les autres vitesses se d\u00e9duisent mentalement.<\/p>\n<\/blockquote>\n\n\n\n

    Vsol<\/th>Temps pour 1 NM<\/th>NM par minute<\/th><\/tr><\/thead>
    60 kt<\/td>1 min<\/td>1.0 NM\/min<\/td><\/tr>
    90 kt<\/td>40 s<\/td>1.5 NM\/min<\/td><\/tr>
    120 kt<\/td>30 s<\/td>2.0 NM\/min<\/td><\/tr>
    150 kt<\/td>24 s<\/td>2.5 NM\/min<\/td><\/tr>
    180 kt<\/td>20 s<\/td>3.0 NM\/min<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

    Exemple :<\/strong>
    \u2192 \u00c0 120 kt, tu es \u00e0 12 NM du point d\u2019approche \u2192 6 min avant arriv\u00e9e (12 \u00f7 2).<\/p>\n\n\n\n

    \n\n\n\n

    \ud83d\udccf 4. Conversion rapides<\/h2>\n\n\n\n
    Conversion<\/th>Valeur \u00e0 retenir<\/th><\/tr><\/thead>
    1 NM<\/td>1.852 km<\/td><\/tr>
    1 ft<\/td>0.3 m<\/td><\/tr>
    1000 ft<\/td>300 m<\/td><\/tr>
    1\u00b0 de lat<\/td>60 NM<\/td><\/tr>
    1\u00b0 de long<\/td>60 NM \u00d7 cos(lat)<\/td><\/tr>
    1 hPa de diff\u00e9rence de QNH<\/td>\u2248 27 ft<\/td><\/tr>
    1 kt<\/td>\u2248 0.5 m\/s<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

    \ud83c\udf21\ufe0f 5. Temp\u00e9rature et altitude (ISA)<\/h2>\n\n\n\n
    Temp\u00e9rature<\/th>Effet sur altitude<\/th><\/tr><\/thead>
    Air froid<\/td>Indique trop haut<\/strong> \u2192 r\u00e9el plus bas<\/td><\/tr>
    Air chaud<\/td>Indique trop bas<\/strong> \u2192 r\u00e9el plus haut<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

    R\u00e8gle rapide :<\/strong><\/p>\n\n\n\n

    \n

    4 ft \/ 1000 ft \/ \u00b0C d\u2019\u00e9cart \u00e0 ISA.
    Exemple :
    ISA \u201310\u00b0C \u00e0 5000 ft \u2192 erreur = 4\u00d75\u00d710 = 200 ft trop haut<\/strong>.<\/p>\n<\/blockquote>\n\n\n\n

    \n\n\n\n

    \u26c5 6. Gradient de mont\u00e9e \/ descente (terrain \/ obstacle)<\/h2>\n\n\n\n

    Formule :<\/strong><\/p>\n\n\n

    \n
    \"\"<\/figure>\n<\/div>\n\n\n

    Mais pour simplifier :<\/p>\n\n\n\n

    Gradient<\/th>\u00c0 120 kt (NM\/min = 2)<\/th>Taux de mont\u00e9e \u00e9quivalent<\/th><\/tr><\/thead>
    3 %<\/td>300 ft\/NM<\/td>600 ft\/min<\/td><\/tr>
    4 %<\/td>400 ft\/NM<\/td>800 ft\/min<\/td><\/tr>
    5 %<\/td>500 ft\/NM<\/td>1000 ft\/min<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
    \n\n\n\n

    \ud83d\udce1 7. Radio-navigation (VOR \/ DME \/ intercepts)<\/h2>\n\n\n\n

    \ud83d\udd39 A. Interception de radiale<\/h3>\n\n\n\n

    R\u00e8gle mentale :<\/p>\n\n\n\n

    \n

    Double l\u2019\u00e9cart d\u2019aiguille en degr\u00e9s pour le cap d\u2019interception.<\/strong><\/p>\n<\/blockquote>\n\n\n\n

    Ex : aiguille d\u00e9vi\u00e9e de 10\u00b0 \u2192 cap d\u2019interception \u2248 20\u00b0.<\/p>\n\n\n\n

    \n\n\n\n

    \ud83d\udd39 B. Temps pour DME<\/h3>\n\n\n\n
    \n

    Temps (min) = Distance \u00e0 parcourir \/ NM\/min
    \u00c0 120 kt = 2 NM\/min.
    Ex : 10 NM \u2192 5 minutes.<\/p>\n<\/blockquote>\n\n\n\n

    \n\n\n\n

    \ud83e\udded 8. Taux de virage standard (Rate 1 turn)<\/h2>\n\n\n\n

    Un virage standard = 3\u00b0\/seconde<\/strong> \u2192 360\u00b0 = 2 minutes.<\/p>\n\n\n\n

    Formule :<\/strong><\/p>\n\n\n

    \n
    \"\"<\/figure>\n<\/div>\n\n\n

    Ex : \u00e0 120 kt \u2192 inclinaison \u2248 12 + 7 = 19\u00b0<\/strong>.<\/p>\n\n\n\n

    \n\n\n\n

    \ud83e\udde0 9. R\u00e9sum\u00e9 : les 10 formules IFR \u00e0 savoir par c\u0153ur<\/h2>\n\n\n\n
    Situation<\/th>Formule mentale<\/th>Exemple<\/th><\/tr><\/thead>
    Plan 3\u00b0<\/td>Altitude = 300 \u00d7 Distance<\/td>10 NM \u2192 3000 ft<\/td><\/tr>
    VS plan 3\u00b0<\/td>VS = \u00bd Vsol \u00d7 10<\/td>120 kt \u2192 600 ft\/min<\/td><\/tr>
    D\u00e9but descente<\/td>(Alt perte \/ 1000) \u00d7 3<\/td>6000 ft \u2192 18 NM<\/td><\/tr>
    Virage standard<\/td>Inclinaison = V\/10 + 7<\/td>100 kt \u2192 17\u00b0<\/td><\/tr>
    Crosswind<\/td>Vent \u00d7 sin(angle)<\/td>20 kt \u00e0 30\u00b0 \u2192 10 kt<\/td><\/tr>
    Temps = distance\/vitesse<\/td>10 NM \u00e0 120 kt \u2192 5 min<\/td><\/td><\/tr>
    1 NM =<\/td>1 min \u00e0 60 kt<\/td><\/td><\/tr>
    ISA temp\u00e9rature<\/td>4 ft\/1000 ft\/\u00b0C<\/td>\u201310\u00b0C \u00e0 5000 ft \u2192 200 ft erreur<\/td><\/tr>
    Gradient mont\u00e9e<\/td>3 % = 300 ft\/NM<\/td>600 ft\/min \u00e0 120 kt<\/td><\/tr>
    Interception radiale<\/td>2 \u00d7 \u00e9cart CDI<\/td>aiguille 10\u00b0 \u2192 cap +20\u00b0<\/td><\/tr><\/tbody><\/table><\/figure>\n","protected":false},"excerpt":{"rendered":"

    \ud83e\uddee Les r\u00e9f\u00e9rences de calcul mental IFR (valables pour petits avions IFR, monomoteurs, IR(A), CB-IR) \u2708\ufe0f 1. Gestion du plan de descente (le plus important) \ud83c\udfaf Objectif : Savoir quand commencer sa descente et \u00e0 quel taux descendre pour suivre un plan (g\u00e9n\u00e9ralement 3\u00b0). \ud83d\udd39 A. R\u00e8gle des 3 % \/ 3\u00b0 Plan standard : 3\u00b0 = 5 % =<\/p>\n

    Read More<\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"parent":0,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-2420","page","type-page","status-publish","hentry"],"jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/acriv.org\/WP\/wp-json\/wp\/v2\/pages\/2420","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/acriv.org\/WP\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/acriv.org\/WP\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/acriv.org\/WP\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/acriv.org\/WP\/wp-json\/wp\/v2\/comments?post=2420"}],"version-history":[{"count":1,"href":"https:\/\/acriv.org\/WP\/wp-json\/wp\/v2\/pages\/2420\/revisions"}],"predecessor-version":[{"id":2428,"href":"https:\/\/acriv.org\/WP\/wp-json\/wp\/v2\/pages\/2420\/revisions\/2428"}],"wp:attachment":[{"href":"https:\/\/acriv.org\/WP\/wp-json\/wp\/v2\/media?parent=2420"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}